I have an Ender 3 V2 and this happened once. It is important that the nozzle is up to temp for the type of filament being used.
If you can see the broken part before the extruder then release the roller (pressure) on the extruder which you normally do by squeezing he lever with the spring and then using a pair of pliers pull the filament out of the bowden tube. This is why it's important to ensure the nozzle is up to temp or you could damage it.
If you can't see the filament then remove the blue clip on the coupler attached to the extruder, with nozzle heated press the leaver to release the pressure on the filament and press then white plastic ring around the extruder in while at the same time pulling the tubing out of the coupler. You should now see any filament where you can then pull it out. Re-attach and load new filament.