When I bought, the USB function works well.

But lately I unpluged the cable suddenly while it was connected to PC in Mass Storage mode.
That was my mistake because after that I can not use the USB settings function any more.

Whenever I tap on the USB settings function, my phone reboots automatically.

Now, when I connect the cable, the PC does still regconize it but I can not set it to PC Samsung Studio mode to use TKExplorer.
Help please..