How can I fix my Black & Decker Hedge Trimmer LHT2220?

It's a 20 Volt Lithium Battery machine
The switch specifications you give are for mains power - not that that matters - they just use the switch that suits them best - one they can get more cheaply perhaps.

The specification SPDT stands for Single Pole (switches one wire) Double Throw (two positions with a common terminal)

Any switch that fits will do - you may do best to buy the correct switch from a B&D spares outlet.

Given that the cutter has moving blades there are safety issues so the switch will very probably be a momentary switch - let go and it turns off.

Defond DMU 1215 refers to the switch - some of these are available on e-bay.

You might also take the switch into an electronics hobby shop - Maplins for instance - and ask for the closest match.
Amazon have similar switches too. Buy 5 for £3.22 - free delivery!

Do not worry too much about the voltage and current ratings

Good Luck...
May 2016