Acrobat Reader suddenly won't open ANYTHING

I use a Mac and unless Reader automatically updates, I didn't update or make any changes except try to open a PDF file I just transferred to my computer from my laptop.  It's a working file on my laptop, and as soon as I saw it wouldn't open on my computer, I tried to open any file I have, including some I've used in the past week, and nothing happens at all.  The only thing that occurs is that the thumbnail for the application loads on to my computer menu bar as it always does.  Otherwise, I go to the File menu or the computer files and click on something to open and after I click there is simply nothing but my desktop.  I DID check for updates and it may have done one (already can't remember for sure since I've been fiddling with this) but at this point it is up to date.