Whoa, whoa, whoa... slow down.
Not enough info. In your first post you make some general claim as to what happened without any of the details.
1. What was happening (ie - what did the screen post) when you tried turning on the PC, and it didn't load Windows?
2. What was your method of installation for GRUB? What variant of GRUB did you use? And finally, what exact
message did GRUB post when it failed to boot the OS?
If you can't be bothered to at least answer that, you may look into the Neosmart recovery discs
for Windows Vista/7. They were designed for the exact situation where an OEM disc didn't have a recovery option. They could reinstall the bootloader, and repair the MBR. While they used to be offered for free, there's now a minimal $10 fee to download them. Although... an unscrupulous search will still return the original downloads out there in places.Edited by Who'sThere - 6/4/12 at 11:46am