I have a Dell PC, which is about 4 years old. When booting up it never launches Windows. I would like to wipe the hard drive and re-install windows. (I want to do this mainly to learn a bit more about PCs. I already have another PC and just want to get this one working again, so that I can give it to a family member, there is no important data on it that I would like to save).

Why will it not launch windows when booting up?

have you got the operating system disks? if you have it depends on what O/S you want to put on but you'll need to format the drive to clear all the data

What OS do you have for that PC?