Computer can not detect my phone through usb cable
When I first bought my HTC Desire 820 G Dual SIM, I had no trouble connecting it with my computer. In fact it happened automatically. But recently I found out that when I connect the phone with the HTC usb cable (and I have tried other usb cables to make sure it's not an issue with the cable), there is no option to connect the phone's usb drive to the computer (I've swiped down the screen- the notification does not appear), the phone does not show up under 'MY COMPUTER' or 'THIS PC', although the phone battery is charged. I installed HTC Sync Manager on my laptop, but the software when launched says there's no HTC device connected(after I connect the phone).
1.Phone is charging
2.I have installed HTC Sync Manager,- no avail
3.My laptop can connect with my phone via bluetooth
4.I have tried different computers and different data cables to make sure that the problem is with the phone itself.