reboot means to restart the computer, you mean format and restore to factory
settings.
To do this you will need your restore disc that came with your computer,put
it in your drive, restart the computer and follow the on-screen instructions.
Some machines do not come with a restore disc, you may find your computer
has a hidden partition instead, check the programs list in the start menu for
a program that sounds or looks familiar to restore.
You could also visit your computers manufacturer website and download the
manual for your computer, it will give you instructions on how to restore
your computer back to factory settings.
Hope that helps ?
Andy W