1.Go to the bios by pressing Del or F2 or whatever key your model have to get to bios.
Check boot order , make sure first is your hard drive on the list. Save .Restart. Does it open? if not check 2.
2. Put your Win XP cd in, go to bios, put your Cd rom as first boot. Save. Restart.
Press R while cd loads.
You're in Recovery console. Type for your Windows instalation (usually 1)
And enter password. If you don't have any, then press Enter key.
chkdsk /r and press enter.
To see other options press chkdsk /?