I'm Messed up the measures somehow

Hi Person(s):

I'm working on my 1st symphony. I can't get rid of the measures crosses the "21". I'm completely new to Musescore. This is my 2nd day of using it. Attached is the measure I'm stuck at. How do I reveal the measures. I must have hit a wrong button. I can't seem to undo whatever i just did to make "21" appear on the last measure.