Boot from the Windows DVD or a repair CD (you may have to change the first boot device to CD/DVD in the BIOS), answer a few questions, select the Repair option in the bottom left corner and choose:
1. Startup Repair (you may have to run it several times).
2. If the above doesn't cure the problem, go back to the Repair Option and this time choose Command Prompt, then type these 4 commands:
BOOTREC /FIXMBR and press Enter.
BOOTREC /FIXBOOT and press Enter.
BOOTREC /SCANOS and press Enter.
BOOTREC /REBUILDBCD and press Enter.
3. If it’s still not successful or you receive ‘No operating system found’ or ‘Element not found’ messages, go back to the Command Prompt and make the partition active by typing these commands:
DISKPART and press...