Computer

Hook car up to obd2 port at dealer or private show. There are other ways to do it youself such as carvista etc. Do a good search on obd2 reset.

You can do it using the Saturday mechanic method. With the ignition switch off remove the positive terminal on the battery, wait about 15 minutes, replace the terminal, turn ignition switch to on and wait a few seconds, then start the car. With this method, you will probably have to reprogram the radio and clock. I don't know if this will solve the problem of the speedometer not working, but give it a try.