what? my computer is turned off?

hello its me again..well last nite about 7:30 pm had my computer on but i had to go to walmart. i got back at like 9 pm and my computer was off. i ask my mom and my dad if they turned off my computer and they said no..on bios i have the max temp at 90c for shutdown but i dont think my computer got that hot.
why did this happen? do i have a setting for the computer to shutdown in a certain time that i dont know about?

any help would me great

 

Are you it was not on standby?

 

there could have been a split second power failure that your parents didn't notice ... it might be set to hybernate which saves everything in your RAM and shuts down automatically

 

ok ill keep an eye on it....ill leave it on gor to hours tomorrow then ill come back
and see it if still on

it was not in stand by