Got a used laptop want to restore it to factory setting

Well use of the Restore discs would be your first port of call.

Many laptops have a hidden Recovery Console builtin. As you first boot, try tapping F10 or F8... see if you can get a recovery option to fire up.

If so, you will be given onscreen options for recovering just the Operating System or restoring the computer back to "just opened the box" status... a factory reset.

Go with the factory reset.

If you have an install disc for the operating system, you're best off zeroing out the hard drive then installing with a totally clean system.

Be sure to visit the website for the laptop brand and download all the drivers for that laptop, have them ready to install when you try to do a clean OS install from a generic disk. Laptops are notoriously more problematic for clean installs versus desktops. Not impossible, just more problems can occur. Best to have those drivers handy already.

Just to make this more fun, I really find it necessary to add that just because you download those drivers, doesn't guarantee they'll work. I've downloaded drivers from either the computer manufacturer's site or the device manufacturer's site, and despite being what it's supposed to be, doesn't end up working.

I think it's chancey wiping out a computer and hoping all those drivers work, unless everything in it is pretty common stuff. You haven't ever said what this laptop is, so that someone may have a better idea. I would never have purchased it used without knowing I had all the restore disks or restore partition. (Well, I also don't know that it wasn't given to you.)