Apparently, something terribly wrong happened to your software - this could either be a software-level problem or a hardware-level problem.
If it is a software-level issue, you can simply try to re-install the OS using the Lumia Software Recovery Tool, connecting your phone to your PC.
If this is a hardware-level issue, then the only solution is to take your phone to a service center and have them diagnose and repair the problem.
Should you wish to provide additional information or ask further questions, create a Windows Central account and then respond in this thread.