How do you turn off the mute on a mercedes c240?

C240 mercedes benz key wont turn?

• I insert my key fob and it wont turn...locks up..only after many many tries it finally turns....

• Answer:

  As mentioned above, the easiest way to troubleshoot this is to try your spare key. If the other key works right away, you've isolated the problem down to the first key. If both keys have trouble starting the vehicle, the problem is likely the EIS (electronic ignition switch). The only fix in either case is to replace the key or EIS. Neither can be repaired nor reprogrammed.