well HDD is what you want to boot from but it sounds like some data got deleted. will it boot into windows at all? if not then we can rebuild the boot loader or maybe allow windows repair to try and fix things.
you can insert your windows 7 disk and click on repair, let it run through and see if it can fix it. if it does great, if it does not then post back here and i can tell you the commands to run to rebuild all the boot files