HTC Titan capacitive buttons not working. Why?

[Windows Central Question]

I have an HTC Titan windows phone running Windows Phone 7.8, and today suddenly my phone restarted and said welcome and stuff! Things didn't get deleted except the Windows Live ID but my apps and others were there, and my start screen appeared to be rearranged. And now the back, start and search keys are not working!! Please guys help me as soon as possible.