Re-install Windows. If you pick the "Custom Installation" option it should save the data from your previous install to a folder called Windows.old located on your C:\ drive.
If you want to back-up your data before attempting the re-install then use Ubuntu (Linux).
You can find the download link and the instructions on how to create a "LiveCD" (or a USB drive) here: http://www.ubuntu.com/desktop/get-ubuntu/download
If you want to back-up your data before attempting the re-install then use Ubuntu (Linux).
You can find the download link and the instructions on how to create a "LiveCD" (or a USB drive) here: http://www.ubuntu.com/desktop/get-ubuntu/download