Been through the same thing, and was too easy and took me 20 minutes to solve after 4 hours of research.
1- First install the operating system GParted Live on USB: GParted -- Download
2- Use the GParted app on the desktop to check your hard drive. If there's no NTFS allocated partition (probably C drive you installed Windows in) that is apparent, then the problem is obvious.
3- Close GParted and open Terminal on the desktop. Run the command testdisk. It can modify your hard drive. Just repeatedly press enter at every screen, without having to use up down arrows and different options. It will analyze
your drive and partition tables by default. It does not format the drive. No files will be lost.
4- Now close Terminal when done and check back to GParted. Your hard drives C: and D: will be back. Shrink/extend the volumes the way you like it and shut down GParted Live. Use another USB to install windows 7 back as it is.
I think this is the best you can do with a hard drive that is corrupt, as your PC says "file system not recognized"