If you want to reinstall boot loader use the one of the following methods
Simply boot the Windows 7 DVD, then, after the language choise, choose in the bottom left corner the button “Repair my installation” or something like that.A little menu will open up and one of the choices is “Repair startup”. This procedure will rewrite your boot sector and will replace the boot files.
If this doesn’t work, try to boot again and choose “Open command prompt” from the above menu then write Bootrec /RebuildBcd command
Use vista boot pro software to do anything with boot loader. software can be used for win XP, VISTA AND 7.
You can download from here
you just went into the recovery console and type fixmbr