you need to look at Windows Vista's Repair Your Computer options.
* Startup repair - This automatically fixes problems that are preventing Windows from starting
* System Restore - This will Restore Windows to an earlier point in time
* Windows Complete PC Restore - This will completely restore your entire PC - programs, system settings and files - from a back up that you have previously created (Available in Windows Vista Business, Enterprise and Ultimate editions only)
* Windows Memory Diagnostic Tool - This checks your computer's memory hardware for errors
* Command Prompt - This opens a Command Window
Windows Installation Disk
With the Complete PC Restore Option you must have made a backup of your system, either on your hard drive or on a set of DVDs, in order to use this option. If you don't have a backup then don't use this option
1/ make sure your PC can boot directly from the Vista DVD. Obviously, most modern PCs can. With older machines you may need to check the PC's BIOS
2/ Start the PC
3/ Immediately insert the Windows Vista DVD into the DVD drive
4/ A Black screen will appear with the words 'Press any key to boot from CD or DVD'
5/ Press Any key to start the booting process
6/ A new screen will now appear with a progress bar. The legend say's 'Windows is loading files'
7/ After a few minutes the Microsoft copyright window ill appear and another small progress bar will be visible
8/ You will next see a Blue curtained screen
9/ After a short while the Language option screen will appear
10/ Select your language and keyboard language and the Click the Next button
11/ At the bottom left of the next screen - the Install screen, Click on the Repair Your Computer option
12/ The System recovery options will now search for your Windows Vista installation
13/ Once the Vista installation has been located, Highlight it and then Click the Next button
14/ You are now presented with the set of recovery options
15/ Click on the Option you require and follow the onscreen prompts