Why does your screen go off so often?
If it is just the monitor that is shutting off, then there might
be a problem with the monitor with staying on. If by 'screen', you
mean the actual computer goes off and produces a black screen, then
your computer might be set to go into hibernation quickly, or it
might have a mode where it goes into a blank screen saver quickly.
Check the computer's settings to fix that problem.