dell clean install

Solution
If the laptop came with Windows 7, then click the following link to download a Windows 7 ISO. You will need to enter your Windows 7 product code which should be on the underside of the laptop. Burn the ISO image to a DVD or copy it to a USB drive to install.

http://www.microsoft.com/en-us/software-recovery


If your laptop came installed with Windows 8 (8.1), then click the following link. You will need a USB drive or a DVD burner. The program will not allow you to save the Windows 8 ISO image to your hard drive. No need to worry about entering a product code because it is embedded into the laptop's BIOS which will likely be verified during the installation process...
If the laptop came with Windows 7, then click the following link to download a Windows 7 ISO. You will need to enter your Windows 7 product code which should be on the underside of the laptop. Burn the ISO image to a DVD or copy it to a USB drive to install.

http://www.microsoft.com/en-us/software-recovery


If your laptop came installed with Windows 8 (8.1), then click the following link. You will need a USB drive or a DVD burner. The program will not allow you to save the Windows 8 ISO image to your hard drive. No need to worry about entering a product code because it is embedded into the laptop's BIOS which will likely be verified during the installation process.

http://windows.microsoft.com/en-us/windows-8/create-reset-refresh-media


Before doing anything, download the appropriate drivers from Dell before doing this otherwise, you may find that your laptop will not be able to connect to the internet because there are no drivers for your ethernet / wireless controller.
 
Solution