Windows only go half way up and stop?
Do the windows make any noise like they are binding or are they quiet?
If the windows will still go down, I would not think it was just the motor, but it could be a problem with the drive cables. They may have become frayed or may have gotten jammed or off track on the drive pulley.
Sounds like you are going to have to remove the door panel for a closer inspection of the whole regulator assembly.
If it is something obvious, you might be able to see what is going on by removing the rubber plugs in the bottom of the door and looking up into the door from there.





