My Book stalled backup

I am trying to use My Book for the first time for backup, it has stalled about halfway through the back up. Should I just let it run, is there something I can do to get it to finish?

What is the name of the application you are using to copy your files? Can the unit still be accessed manually in Windows Explorer, or does it prevent access when the copy process stops?

This is my 2nd day with MyBook 8T. I backed up some files successfully yesterday. Today I tried to back up some more but it stalled at 59.9 Gig out of 260 Gig. 23% complete. I can’t pause it or stop it. I don’t know what to do! It is running, but not changing for hours.