The very first thing to try -- Try a different USB Phone-to-PC cable.
I once spent hours trying to connect my Samsung Galaxy III phone to my laptop and could not get it to work, only to figure out later that same day that the USB "Phone-to-Laptop" cable was bad. The end that plugs into the phone had a bad connector on it.
Next to try - different USB ports on your PC. Try each and every one. If something else is plugged into one of the PC's USB ports, unplug it and plug in the phone USB cable to the PC USB port.
Last item - uninstall/reinstall the USB driver.
From Device Manager (devmgmt.msc) - Open the Driver tab and then click the Uninstall button. This will remove the USB controllers driver software from your system.
Next, the driver must be reinstalled. Close the smaller window for your USB device and in the main Device Manager window click Action > Scan for hardware changes. Windows will notice that the USB device is lacking driver software and will reinstall it.
After that's done, you can click on the USB device again and under the Generaltab and under Device status it should now say the device is working properly.
Also, to reinstall the driver, you can simply re-boot the system after you have uninstalled the driver.
Good Luck to You!
Regards. . .
jcgriff2