You need to look at Windows 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
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
How you access the repair options will depend upon whether you have a Windows installation disk or whether your operating system came pre-installed by your PC manufacturer.
Pre-Installed Options NOTE
If no repair options are available your PC manufacturer may have replaced the tools or customised them. Check your Computer Manual before proceeding.
1/ Start your PC
2/ If your PC has one operating system Press and Hold the F8 key as your PC starts. If the Windows Logo appear you will need to start again
3/ If you have a dual boot system a Boot option menu will appear. Highlight the Vista operating system and Press the F8 key
4/ In both cases, if all has gone well, an Advanced options screen will now appear
5/ Highlight the repair Your Computer option and Press Enter
6/ Select a keyboard layout, and then Click the Next button
7/ Next select your user Name and Enter your Password, then Click OK
8/ The recovery options should now appear