Running chkdsk on a file system that is severely corrupted can result in data loss. If you have important data on the computer then back it up if not done so already.
You can run chkdsk from an install disk of Windows 7. If you do not have an install disk then burn the iso of your version which you can download using this tool.
If you have a live linux distro boot disk you may be able to force a chkdsk. Because you only have one hard drive on the computer your drive will be listed as sda and the partitions as sdaX where X is a number. For Windows 7 you may have 3 partitions.
You can find your partitions in terminal by typing
This all lower case and it is a "L" and not a 1.
Open a terminal and type the following command.
Do this for each partition on the disk, i.e. sda1, sda2, sda3. Reboot into Windows which should force chkdsk to run.