If your files are on a separate partition other than your Vista Installation, boot up and reinstall Vista over the previous installation.

If you only have one Partition, follow the instructions in the provided link carefully to create a partition (make sure you give big enough file space):

http://www.zolved.com/synapse/view_c..._Windows_Vista

Then move your important files to that safer partition and reinstall Vista over the old one.

Extra partition will secure your backup files as well as act as storing location in future for unwanted or important files.