First, go into the BIOS and check out the boot order. Ensure that the hard drive is listed as number 2 behind the cd/dvd drive. If it is, then it could be that there is an issue with the hard drive or malware took out the OS. If you want to do a system restore to factory conditions, turn the computer off, hold down 0 and then turn the computer back on. You should get a set of options and you'll want to select restore my computer to factory conditions.