How do people find reasons to stay alive?
Do you feel that you have no reason for living?
I don't know what the point is of existing.
It sounds like you're feeling very bleak about your life right now. Please find something that will give you the motivation to move on with your life, or speak to a professional about this.
Do you think I should play games or watch tv to feel better?
If that's what you do to enjoy your time, then yes!  Or whatever it is that makes you happy.  A mental health professional can work with you to figure this stuff out.