OP, obviously, I don't really know much about your situation, you might have had some really stressful events in your life recently, I don't know.
However, I have a few suggestions which I hope will help.
This will probably sound strange, but you might have to make some changes to your diet. Insufficient nutrition can lead quite quickly to fatigue and depression. Try to make sure you eat at least two pieces of fruit and / or vegetables a day. Supplements in pills form are not really an adequate substitute for fresh fruit and vegetables, because it is much harder for the body to digest them and absorb the vitamins, bioflavinoids and trace elements your body needs on a daily basis.
If you are stressed because of school or work pressures, it is extremely important to let your teachers (or a trusted friend that you work with) know. They might be able to make adjustments to your working / learning environment and schedule which lessens the pressures you are under.
Next, sleeping patterns and exercise : try to make sure you get at least eight hours of sleep every night. I personally find that it I am having trouble sleeping, that I can fix things by doing thirty minutes of intense physical exercise (press ups and situps usually). If you don't get enough sleep, your body chemistry can be adversely affected - you run the risk of hormone imbalances which can lead on to problems with your metabolism, which you really do not want to experience.
Finally, this is going to sound trite and cliched, but here goes anyway : Give the situation TIME. Events that seem unbearable at present will become easier to deal with as time passes. Time gives you perspective, a changing viewpoint.
Problems you have may seem impossible to cope with at present, but if you try to break the problem down into something that you can deal with gradually, in incremental stages, then you might start to think of possible solutions. I find that I helps to make a list of your problems and then write down another list of possible actions to take to combat or resolve the problems, but maybe that's just me.
Just hang in there, don't panic or freeze up, keep fighting and keeping on, but don't try to fight your battles all at once, just take things a day at a time.
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