my daughter was working on her com  it i dell 2400 running win xp home and said she wanted to make her  monitor resolution better anyway she clicked on some things  and now her monitor will not work.  I know the monitor still is good because I tried it on my computer and works fine. I think she somehow disabled the monitor so that the com is not using it, is there a way to disable/enable monitor in win xp? If so I cannot find a way to bring it back , even re-loading win xp does not help, all it does is go to the "windows starting " page and then goes blank. I can get to f2 and f12 page but cant find anything there that will enable monitor . And I cant adjust windows if I cant see it.. How do I fix this...please help, surely someone has had this happen before

any more info you need and I will try to give it as soon as I can but please help