1- Boot from the corresponding windows 7 repair cd and open command prompt
2- Type chkdsk :”disk drive letter” /f
3- Then reboot
4- Now do a startup repair when the windows open up and the windows system disk is shown
5- If it doesn’t work
6- Open command prompt and type the following “cd drive letter”:\ copy bootmgr “system disk:\”
7- Reboot and do startup repair again it should now work.