2002 mercedes-benz wont take my key

it is integral to the transmission , i've put a link to a video , shows the basic procedure so you will know if it's something you could do or get a mechanic
Mercedes Benz Transmission Control Module Replacement

sounds like your instrument cluster is not going to sleep have seen this problem it will also drain your battery if you don't drive the car everyday

Try checking the key reader it's usually a plastic ring around the key barrel. If it's dies will not read code in key to enable the car to start. Check your key is sending a code as well.

1. Some times the keys wear out. Do you have a spair key you can try.
2. Turn the steering wheel back and forth while trying to turn the key sometime the steering wheering lock will bind.
3. Now the bummer part is the ignition lock will have to come out so you can determine what part froze up.

I have a 2001 C240 with the same issue. I removed the positive battery cable from the battery and kept it off for 30 seconds then replaced it. Everything was reset and the key worked.

have you tried replacing the battery?

merc 220 wont turnover.new battery ignition lights come on then turn key nothing happens?

Yup, either NO fuel or NO spark !!

check for fuel pump operation.have someone turn ignition on while you go to rear of car where fuel tank is to listen for fuel pump operation.if not.check fuse and relay.if you hear fuel pump .check ignition system to make sure engine is getting spark.

I have a 2002 C240 Mercedes and need to replace the cabin air filter. Problem, I don't know were it is located or how to replace it. Can you help me.