Help with System Restore Windows XP

I have an old inspiron 1150 and I am trying to do a complete system restore- setting it back to original settings.  I havecompletely backed everything to an external hard drive.  The directions tell me to hit control and f11 at the same time and then release at the same time.  Nothing happens axcept the regular boot.  I hit these keys when I see the dell screen.  I've also tried it at different points- nothing happens.  I've tries different F keys as well- I still don't find system restore.  PLEASE HELP- I need to get this computer running better and soon.  THANK YOU!