The headlamp washers are lifted by hydraulic water pressure. They're fed by a separate high pressure pump in the washer bottle. If they're not popping up, there could be several reasons:
You may have insufficient or frozen water in the resevoir.
One or more of the pipes could be disconnected or split.
The hydraulic jet raising device could be siezed (frozen?).
The pump isn't working. (fuse?)
First things to check for would be: Ice, water on the ground under the offside front wing or front of the car, and can you hear the pump running when you operate it.
I needed a new headlight washer pump for my MW a few months ago and found that the complete resevoir including headlight and windscreen washer pumps was only £3 more than buying just the headlight washer pump.
Dave.