The latest version doesn't work on my computer.

I updated Musescore a couple of days ago, when the latest version was released and has since not been able to use the Musescore. It doesn't work properly; I can't access any menues, can't change the size of the score, can't mark a bar, can't click on a note etc. It's like if it is half stuck someswhere.

In other words, I need to go back to the older version, but how do I do that?