Reformat old computer hard drive

I was thinking of the f8 or f12 key when the computer starts, there is nothing worth saving or backing up since all the flight simulator program has been backed up from the time that it was installed, I need to completlly erase the hard drive, I tried with the XP progam and it would not work, it is a virus the tells me it does not recognize the monitor or the mouse, and I still see what there is on the monitor and the mouse works, it just drives me nuts with the stupid mesages, it does not have a connection to the internet, wife wanted to see what there was in a usb stick that see got from a friend and that gave the hard drive the cold.

Is it f8 or f12 the comand to reformat the hard drive when you turn it on?

Thanks again I am learning new things, there is hope!

navegator