Hi Cheldra! Wish I could give you some wise advice, but I'm having the same problem. We've defeated Kormak 3 times and I still can't unlock Hrothgar either. Was coming here looking for answers and only find questions. Hope somebody knows why this isn't working!
I was looking thru this forum and about 10 pages back they were discussing this problem. It turns out you have to be standing in just the right spot when you try to unlock Hrothgar. Move back and a little to the left until you get a box that says 'click X to unlock cage'. I just tried it and it worked for me :D Good luck!