A silly answer (but then you can't spell windscreen!)
Is there water in the tank? Easily checked, top right engine bay.
Does the pump come on?
No, check fuses, check power at the pump (on side of tank), replace pump.
Yes, pull the pump out of the tank, it might be clogged with dirt. Check the piping it could be kinked or the nozzles blocked. If it runs but doesnt pump, replace it.
Jmmy
August 2008