Hi newcomer and welcome to the Tom's hardware forum.
Try this, I read in another thread
Open "System Recovery Options" on the repair disk, or OS disk.
Open up the Command Prompt.Try typing the following commands in order:
1- bootrec /fixmbr and hit enter
2- bootrec /fixboot and hit enter
3- bootrec /rebuildbdc and hit enter
Reboot the PC and try to boot again.