Get a PS3 or XBox 360. Sounds like a PC is too complicated for you.
That was unnecessary and unneeded. Just because someone doesn't have a very high knowledge of computers doesn't mean they shouldn't receive adequate assistance with any problem they may have.
Is this an older computer? Sometimes power supplies have a tendency to go out after a few years, happened to an old compaq I had laying around here. Other than that it could be numerous things that would cause your pc to crash. Unless you have spare parts laying around that you can swap in it might be a bit difficult to pinpoint the problem.