computer shut off in middle of search now won't start up

[sodbuster2x]

My sister-in-law was doing search for a new car and all of a sudden her computer shut off and we can not get it to boot back up tried to go in thru safe mode but it just locks up can not select anything. Can some one give me some help please I thought about trying to reformat hard drive but thought I'd seek your help and advice first. she has avast antivirus on computer but said it has been doing funny things for the last week and running very slow.
thank you for your time.

[Geek-9pm]

A virus would make it run sow. But if if cn not turn on it must be a hardware or mechanicla problem. Maybe the switch is broken?
You do mean that the screen will not light up?
Or the computer starts, but Windows will not show up?

[sodbuster2x]

sorry about that, it will turn on but locks up tried to go into save mode but locks up when it comes to the screen that u can select to go into safe mode.