Before selling a used laptop, learn the specifications of the laptop, inspect its condition, and wipe the contents of the hard drive. To find out the specifications of a Windows laptop, go to Control Panel, click System and Security, and click System.
Check if the laptop can power on, and inspect its case for cracks and scratches. Check all the keys on the keyboard, and see if they work properly. Also, check the display for dead pixels. Remove all personal information from the hard drive using a third-party eraser, such as Darik's Boot and Nuke. Reinstall the operating system of the laptop for more data security.