Are you on Windows 10 TP?
If yes, then it is a known bug. Some users were able to fix this issue by performing a hard reset.
But still, you may consider performing a soft reset once, and check if the problem is solved.
To perform a soft-reset: Hold down the "volume down" and "power button" for 10-20 seconds (till the screen turns off).
Let me know if this helped.
Have a good day!