My computer won't start

Hello,i'm trying to solve the problem with my computer...at boot up it will display that a file is missing or corrupted --CONFIG/SYSTEM32..it instructs me to press 'r' to repair.it only comes back to the boot up screen..and a blue screen will appear. then after that i tried to restart it but nothing happens and worse the monitor won't display anything..i tried to reinstall my win xp os cd but it didn't work..my classmate told me to press f12 and del..is it right? get i get some help...i badly want to repair whatever is going on my computer. i have to finish some school prject..please help me.. thank you!!