Scanner won't scan - says communication problem

I tried to open my scanner but get a message after it warms up
A communication problem has occured. Open the log file to find out more. Where is the log file? I can't find it anywhere.

How did this happen? I was scanning a photo and it put selection boxes around three of the portions of the picture. I wanted to close out of all of them but the scanner froze. So I did a 'force quit" I have a Mac. Now I can't get the scanner to work! Any idea what happened and how I can fix it.

Thanks.