This is Problem in Detecting USB from Mobile to PC

As you plug the USB port from mobile-to-pc, the computer will automatically detect it.

To verify that your mobile is connected to the computer, you must see the USB icon at the top bar of your mobile.
Slide your finger from that top bar and you will see

'USB connected

Phone connected to computer via USB. Tap

the button below to copy files between

computer and Android's USB storage'

Tapping the 'Connect USB storage' will now allow transfer files between your phone and computer.


But if you experience a problem in detecting the USB, the icon will not show up at the top bar.
All you have to do is:

• Keep the USB port connected to your mobile phone and the computer
• Turn OFF your mobile
• Trun it ON again 
• As your mobile power up, you will now see the USB icon.

if the above instruction doesn't work:

•  Unplug the USB port on PC end
• Plug it to the other USB port (PC)