How can I fix my cordless drill switch

Take the battery out/off. You’ll have to disassemble the drill enough to get at the switch and that’s usually a handful of screws, but just make sure you keep track of where they came out from. you’ll need to get to the switch

If you have a multimeter, you could hook it up to the switch on each electrical lead going into the switch. the meter should be set to resistance (Ohms) and squeeze the trigger. You should see the resistance change (likely decrease) as the trigger is moved. If it doesn’t, try and spray in it with some electrical contact cleaner while you are squeezing it back and forth. You’ll want to also double check there are wires correctly soldered to the switch. Re-solder them, if they are really loose or broken off.

BTW - I assume you’ve tried this, but make sure you have full voltage in your battery pack. The switch could be fine but your charger might be lying to you. 😜