Screen problems.

Hi Sven here,
The screen on my laptop has done a 90 degree “flip” and is on it’s side. If anyone has any suggestions on how to restore this I would be most grateful (as will my neck) !!!!
I have very limited computer skills- so please keep it simple! It started about 3 mths ago,and would “fix” itself if I restarted it.It has been 3 days now,with no change.Friends have not heard of this so I’m stuck, if anyone could be of help it would be much appreciated- thanx