I've used this method to remove the password on a windows 7 computer, it's possible that this would also work for windows 8
UPDATE: It looks like I forgot to add the link or for some reason its not listed anymore. Here it is...
I would just leave the phone plugged in for a couple of hours to seek if it will wake up. I had an old phone that hadn't been charged for weeks at least and it turned back on after awhile.