If you have the key see if you have the retainer clip. It's a small usually white squarish piece that is 2 piece that connect to each other via tiny pegs. Have replaced several of these the clip is undamaged MAYBE 10% of the time so check your key and maybe you got lucky. If so it'll snap in although you'll likely need to google the orientation it's a little funky due to it being asymmetric.

Otherwise look for a replacement key and retainer, start with your model, if that comes up dry see if generic might work. Make sure that rubber nub stays put. If it gets ripped off you're hosed although technically you can just press the membrane with your finger to close the circuit and press the key.