Is the temperature set too low?

Or one most people I dont think realise, when you screw the filament feeder back onto the extruder motor, you can actually screw it on in the wrong place.
If it's too far in one direction the filament will not be pushed on to the gear so will just slide through.
It is in the other direction, the bearing is too close to the gear that the filament will not feed through at all and you get the clicking sound, and I think this is what may have happened to yours.

Open up the extruder again, and adjust the feeder by pushing it slightly in one direction, then tighten it back up on the motor.
Before fully reassembling, get a few inches of filament and pass it through, making sure requires a little bit of force but not too much.