Ok, before you freak out.
Please provide me the following information.
Dose the Bios screen comes up?
Do you have any important data?
Are you good with computer hardware?
Do you have access to a CD burner and a blank CD?
Right now it seems that you are able to access the F8 so Ill say the motherboard bios is still fine. You will require access to a OS drive no matter what.
Heres the few possible problems that you could have.
1. Faulty Ram Cards
2. Corrupted Hard drive/sectors
3. Corrupted OS
1. To make sure you don't have any corrupted Ram cards, open up your case and remove each ram cards and placing them back in to check your system, look for a faulty Ram card.
2. If you have a corrupted Hard drive if hard to know until you tries to format the hard drive. Get a OS drive, place it in your CD/DVD reader, boot your system with CD/DVD as first priority and format the Hard Drive. Some times the Hard drive cannot be read and will not show up on the motherboard.
3.This is the most common problem and can be solved with a OS drive and then reinstalling the OS. No buggy other than loosing all your data.
To slowly solve your problem, first get a access to a OS drive, place it in your CD/DVD reader. Then boot into your BIOS screen, change the boot priority to CD/DVD as first. Restart your PC and the Cd/DVD should boot. Continue the setup and then choose the format the Hard drives, after the drives is reformatted, continue to install the OS. If you have problems finishing these steps you can message me.