Windscreen washer not pumping but rear window does

There is usually only one washer bottle and two pumps. Often it is your rear that stops working due to lack of use. However in your case, I'd say yours has either burned out or just corroded. It will be underneath the washer bottle. What you can also check is your washer fuse.

One other thing, have someone work the front washer while you, with the bonnet (hood) open stand at the front and listen for the motor. If you don't hear it, suspect the motor. If you do hear it, suspect the lines from the washer bottle to a junction.