I have a 6 year old Hp Desktop.. trying to restore it but wont go?

I have a 6 year old Hp Desktop.. trying to restore it but wont go?

Iam trying to restore a Hp computer with xp. I put the disk in and it just wants to go to f12 or f2. then the blue screen comes up and say its restarting and just starts over. It wont let me push the f8 safe mode. Is there any other way to just take it all the way down and let it run the restore the disk? It seems like its trying keep going to the f12 or f2 keys? any help?