Hello Iangstock,
Please refer to the article on Restoring Your Computer´s Software to the Factory Settings and try the suggestions mentioned. In case it doesn't work, you would require the disks for Windows Vista from Dell.
**Note: Please ensure to back up all the data from your computer before performing the PC Restore as it would erase everything from your computer.
If you do not have the recovery disks, you may order the disks Here (US Customers only).
Hope this helps!
