HTC ONE hung and can not restart the phone I have a HTC ONE. While using the phone it got hung. And when i tried to use the power button the Display as well got switched off. 

Now When i try to hold the Power button for ten seconds and try to hard restart its of no use. When i connect the phone to a pc via USB i get the device detected sound on windows but HTC One doesnt show its mass storage.

Any way to solve this problem ?
As per XDA here you can perform force restart by doing this.

To reboot the phone without ADB, just hold down the Vol Up and power button for 9 seconds, the phone should shut down.


If this doesn't power down the phone, you can try this. Lot of people has reported success in this method for most of the HTC phones.

Put your phone under a bright light then hold power+volume down. 


If both of them fails, you have to wait till the battery die and let it charge and power on the phone normally.

Hope this helps you. Good luck.