A+: Using System Restore with Advanced Boot Options
If you need to recover users’ files from a system that cannot boot, even in Safe Mode, consider making a BartPE <www.nu2.nu/pebuilder> CD or DVD from the same version of Windows, and use its file manager to copy files or perform data recovery. Also, you might attach the drive into another PC and use the other PC's OS to access the drive.
If you cannot boot into Windows XP, try starting your computer using the Safe Mode option and then click the System Restore link. Click Restore My Computer to an Earlier Time, select a previous restore point, and click Next. This will return your system to a previous state.
You can also start a System Restore with Safe Mode with the Command Prompt option. If you are prompted to select an operating system, use the arrow keys to select the appropriate operating system for your computer, and then press Enter. Log on as an administrator or with an account that has administrator credentials. At the command prompt, type %systemroot%\system32\restore\rstrui.exe then press Enter. Follow the instructions that appear on the screen to restore your computer to a functional state.