OP what have you done? What was the problem and what was the fix?
From your post it appears that either the wiring in the plug was loose and needing a new plug (often happens if you pull on the wire instead of the plug itself to unplug), or that your wall outlet had a loose connection.
We had a old wall outlet that had to be replaced as it was not holding the plug securely. It was not a difficult job as long as you make sure the breaker is turned off. You will just need a screwdriver.