pc wont wake up?

Hey guys and gals, I have an unusual problem I was hoping someone could help me with. My young son is only new to computers and he loves clicking on the screen with the mouse and running his age-appropriate software. The problem is when he is finished, he presses the 'sleep' key on my computer. I haven't used this function is ages and now when my pc goes to sleep mode it wont wake up. No matter what I do it stays in sleep mode and I have to manually turn the computer off.

I think I have a corrupted windows file but I don't know which one or how to fix this. Has anyone else had a similar problem? Any help would be appreciated.

 

Hey guys, me again. Before posting I did a search and found nothing but after posting I noticed at the bottom of the screen 'similar threads' and someone had a similar problem to mine. I wonder why the search didn't work, anyways I have tried disabling power management in BIOS and it still does the same thing.