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1) boot with your windows 7 disk
2) select your language
3) select repair and follow instructions
3) go to command prompt and execute the commands bellow:
bcdedit /export C:\BCD_Backup c: cd boot attrib bcd -s -h -r ren c:\boot\bcd bcd.old bootrec /RebuildBcd bootrec /fixmbr bootrec /fixboot
Reboot