Cant pull my notification bar

Hello Dear Expart, i cant pull my notification bar down.i am having the same problem 15 days ago.But after a few days it fix by its own. Now again i am having the same problem. I almost done every thing, reset hard reset. But it was not working. Only 1/4 inch of my upper display wad not working. Is that hardware or software problem. How can i solve this problem?
Please help me.
Tnx in advance.