Two things to rule out faulty hardware.
(1)Can you still view your pictures in the camera?
(2)Do you confirm - no icon or removable "disk" seen in My Computer, when the camera is connected and switched on? Look fro perhaps a different position or drive letter from the one you used to see. Try even a different USB port in case that makes a difference.
Check in Control Panel > system > devices and look for any yellow marker in the USB part of the list you find there.