--) Insert the Windows installer or recovery disc into your computer, restart your computer, and let it boot from the Windows installer disc.
--) After booting from your installation or recovery disc, skip the initial languages screen, and then click the "Repair your computer" option on the main install screen.
--) On the Choose an option screen, click "Troubleshoot > Advanced options > Command Prompt
--) Type the command below and then press "Enter"
bootrec /fixmbr
bootrec /fixboot
bootrec /scanos
bootrec /rebuildbcd