Firstly, before you go formatting the computer , go to the Gateway site and seek support & drivers for the Model that you have.
http://us.gateway.com/gw/en/US/content/drivers-downloads
Now check your Device manager and download all the required drivers from the website and save onto a USB stick.
Once you're sure you haven't missed out on any of the drivers, you are good to go.
Have a Windows Installation disc handy and go about resetting the whole rig.
PS: And I think instead of just rebooting you mean resetting the whole rig to the way it was the day you bought/got it.