Restore to factory default settings for windows 7 and vista

                                                Vista or Win 7

If your operating system is VISTA / Win 7, press the F8 key when you see the Dell logo. It will take you to the advanced boot menu options, which include 'Repair your Computer'. Select that option and enter your password if asked, then you will see a list of options like 'system restore' and 'command prompt'. The last option says 'Dell PC restore', or something along those lines. Select that option and follow the instructions on the screen. 
If in both cases, the Factory default doesn't work, then your laptop's factory image defaults partition has vanished (i.e., been corrupted / deleted). In this case you will have to reinstall the operating system with the CD or DVD shipped along with the laptop. Follow the link below to install windows XP Pro on your own.

       Start the computer.

          As the computer starts, press the F8 key until the Advanced Boot Options menu appears on the  screen.

       Press the down arrow to select Repair Your Computer on the Advanced Boot Options menu, then press Enter.

            Specify the language settings that you want, and then click Next.

            Log in as a user who has administrative credentials, and then click OK.

            Click Dell Factory Image Restore.

           In the Dell Factory Image Restore window, click Next.

          Click to select the check box for Yes, reformat hard drive and restore system software to factory condition.

                       Click Next. The computer is restored to the default factory configuration.

                       When the restore operation is completed, click Finish to restart the computer.