Screen issue

[lynnecatalina]

My husband has the HTC One, and just a few days ago...Part of his screen stopped responding to touch. A strip the width of a gum wrapper about an inch below the top of his screen no longer works. The pixels still light up but he gets no response. We tried rebooting it and still no luck. Any reason as to why this is happening? We have insurance on it, it's just bothersome and a pain to know that it quit working for no apparent reason.