Most of the strategies for handling such runs assumes two key things. The first is that a bad run of cards does not last forever. The second is that in the midst of the bad run, one's psychological fortitude wears down and the player can no longer maintain an A-game and is instead making various mistakes.
The first assumption, though it has no logical necessity is highly likely to be true. Eventually the cards do stop falling against you in such an excruciating fashion.
The second bears some explanation. I'll call the second assumption "the bad run cycle." What happens in the cycle is that after a certain point, you notice that you have really been taking it on the chin. "Was that the fifth two-outer I've taken on the river today?"
Run together a few brutal sessions and the experienced player quickly recognizes the bad run. Inexperienced players begin entertaining conspiracy theories. Once in the midst of this run, the player begins to expect the suck out and consequently plays defensively and pessimistically rather than aggressively and optimistically.
Two things can occur at this point. One, the bad run ends but the defensive play continues. Two, the bad run continues and the defensive play is actually reinforced. "I knew that flush was hitting; I'm glad I didn't waste money with a bet on the turn."
As time progresses, this defensive play begins to take its toll. The suboptimal play leads to greater losses when the cards continue to run bad, and quite often just losses despite the end of the bad run of cards. Now the suboptimal play becomes the problem. It isn't that the player is still in a bad run of cards; the player is playing poorly, and this poor play leads to a bad run all on its own. The player continues to lose money despite getting a "normal" run of cards. The losses compound and the player loses confidence. Even routine decisions spark terror as all manner of monsters could be lurking under the bed.
This cycle is quite common. Experienced players watch for it, but we tend to be good at lying to ourselves and justifying poor plays. To make matters worse, the very fact that one knows that one might be lying to oneself makes one unable to really determine if it's a case of running bad, playing bad, or some combination. Thus it is usually just safe to assume that one is playing less than the best if the bad run lasts for any amount of time.
There are five common pieces of advice, and all of them are aimed at correcting an assumed deficiency in your play. The first and most popular advice is time off. Since the bad run has affected your decision-making to the point that you are not capable of making the correct decisions, you need a reset of sorts. Time off is akin to switching the power off on the computer and then turning it back on. Just reset yourself mentally. An accompanying advice is to spend your free time reading some poker literature. This adds to the reset by reminding you of the proper plays.
The second most popular advice is to drop a level. For example, you have been playing 200NL hold'em and encounter a losing streak. To get out of the bad run you should drop to 100NL. How is this supposed to work? The idea is that you beat up on the less skilled opponents, regain your confidence and triumphantly return to the old level. Again the assumption is that you are shaken mentally and the strategy is aimed at repairing your mental state.
The third strategy is to manufacture a win streak. How do you do that? If I can't win, then how am I supposed to get a win streak? Well, it may take a little time, since you need just a short run of decent cards and bad runs have a bad habit of not allowing that. You play very short sessions. You walk when you are up, even if the amount is very small. The idea, much as with dropping a level is to restore your confidence. The results of each session are tangible. "Hey, I've won four sessions in a row! I can play this game after all."
The fourth strategy is to play a different game. For example, you normally play no limit hold'em and find yourself in the midst of a bad run. Switch to limit hold'em or pot limit Omaha or stud. Each game has its own skill set. If you are running bad in hold'em because of poor decisions, playing a different game will require a different skill set. The idea is that you forget your problems at the other game, focus in on how best to play the current game, and triumphantly return to the old game when you feel ready.
The fifth strategy is to switch sites (assuming you play online - and if you don't, you should be). This often occurs unintentionally, although I have heard it offered as advice to bust a losing streak. As advice, the strategy is something akin to starting fresh. Your home site is mistreating you (not really, but that's how it feels). So why not try out another site? Again, the idea is to reset yourself mentally. All those bad beats at that other site are a thing of the past. Deposit some money and start anew. I play on UltimateBet and Bodog. I recommend both of those sites.
Do any of these strategies work? Yes and no. They all address your psychological readiness to play the game. They do not affect the cards themselves. Nothing does. Those cards continue to fall randomly and if you continue to be on the wrong end of random, you will continue to lose. In the past, I've taken time off and returned to my bad run like I never even left. I've dropped down, beat the hell out of that level and returned to the old level and my old bad run like I never even left. You see where this is going? The only strategy to overcome a bad run of cards is patience and time. Eventually it will end.
How long is eventually? It can be excruciating. Yours truly is over 16K hands of hold'em at the moment. I recently read a professional player's lamentations over a five-month run. He has it turned around now and is doing very well. I'm eagerly awaiting the same.
Beyond the cards, do these strategies work? Yes and no. How much time can a professional player take off? Not much. The professional relies on poker to pay the bills. No poker means no income and no money. Bankroll management is key to having the luxury of taking a few weeks or months off. If the cards don't cooperate upon return, the run can get even worse psychologically. Moreover, a lengthy break can create some rust, which will lead to mistakes and possibly more losses upon return.
Dropping down a level is also somewhat effective here, but the bad run can always follow you down a level. Not only can you not beat the old level, but you can't beat the easier level. This isn't exactly great for your confidence level. Perhaps you could drop another level? These drops are also difficult for the professional player, but possible with proper bankroll management, so that the player can afford the smaller winnings for a spell. Nevertheless, weaker players make more mistakes and you can take advantage of these mistakes. Your bad run of cards may continue but you may be able to tread water rather than lose money at a lower level. If you happen to be playing for a bonus at an online site, then all the better.
The third strategy of manufacturing a win streak is also a mixed bag. For one thing, you know you are faking it. Playing three 30-hand sessions to win a tiny amount isn't really going to make you regain your confidence; it's only 90 hands, after all. Although I can lie to myself, I don't think I'm this good at self-deception.
The fourth strategy of playing a different game may not be possible or advisable for some. Bad runs can obviously follow you to any game you play. For example, I play hold'em and Omaha. If I've been suffering a string of two and three outers at hold'em, do I really want to sit at an Omaha table? If the bad beats have you frustrated, you really don't want to play a game in which you expect more bad beats than what you have now. Moreover, if you are already playing your best game, is playing a game you don't feel as confident in the best way to regain your confidence? Well, it may not be the best way, but it can be a way.
The fifth strategy also fails to stop the cosmic doom switch, but as a mental reset it is somewhat effective. There's something about starting fresh. Of course, if you are an experienced player with accounts at all the online poker rooms, then this is not always a strategy you can use. New rooms, however, pop up all the time. Both new and old rooms usually have sign-up bonuses; you can find them on PokerWorks.
My recommendation is to experiment with different strategies and find the one that best clears your mind of the negative energy. You may find that a combination of strategies is actually the best. As for me, I've already dropped down, I'm taking a bit of time off, and when I start back, it will be on a fresh new site. I plan to take advantage of one of Pokerworks sign-up bonuses.