I seem to go in cycles, mostly I'll go into complete escapism mode without realising and buy way to many games. Eventually I'll clue in that something is bothering me that I'm ignoring and figure out what it is.
For high-stress but mostly short-term scenarios (exams for example) try to eat healthy, drink a lot of water,get some exercise and recognise that the body's stress response is preparing you for battle and you can totally handle this shit.
For things just generally being fucked up, get some paper and a pen and just start writing. It doesn't matter what just write what you feel. Get it out of your head. It's much much easier to deal with the problem when it's laid out in front of you.
Then make a list of what is in your control and what you can do to make it better and a list of what you can't control. And don't worry about the stuff you can't control, just hope for the best, whatever happens will happen etc etc.
As my Gramps always says "don't sweat the small stuff, and in the end, it's all small stuff"