Installing and uninstalling a lot of software can use up your Dell Inspiron 1721's resources, and may infect your computer with viruses, corrupting your system. A factory restore may be the quickest way to clean things up. This type of restore is also useful when you sell or give away the computer and need to delete personal data and software. Regardless of the reason, performing a factory reset on a Dell Inspiron 1721 is fairly easy.
Restart the Inspiron 1721, and as it begins to boot up, press "F8" to get to the "Advanced Boot Options" menu.
Scroll down, select "Repair Your Computer" and press "Enter." Select the language and click "Next."
Log in as an administrator, if required, and click "OK." Click "Dell Factory Image Restore." Click "Next."
Select the option that says, "Yes, reformat the hard drive and restore system software to factory condition." Click "Next." Wait for the restore operation to complete, then click "Finish" to restart the computer.
If you are selling or giving away the computer, just turn it off instead of clicking "Finish" to restart the computer in Step 4. This leaves it in a state ready for a new user.
A factory restore completely wipes out all data and user-installed software. Back up all data and software you want to put back on the computer.