How do I replace the steering wheel tilt lock on a 2005 c230

Just the key or the whole lock cylinder with key ?

Removal Procedure
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.
Disconnect the battery negative cable.
Disable the SIR system. Refer to Disabling the SIR System
Position the steering wheel half way between the upper and lower tilt stops (if necessary).
Remove the steering wheel. Refer to Steering Wheel Replacement .
Roll back the shift lever seal from the upper and the lower shrouds.
Remove the tilt wheel lever (if necessary). Refer to Tilt Lever Replacement - On Vehicle .
Remove the 2 TORX® screws from the lower steering column shroud.
Remove the lower steering column shroud.
Remove the 2 TORX® screws from the upper steering column shroud.
Lift the upper steering column shroud to gain access to the lock cylinder access hole.
Using a bent tip awl, insert the tip into the ignition lock cylinder access hole.
Turn the ignition lock cylinder to the START position.
Using the bent tip awl, push down on the ignition lock cylinder retaining pin.
Release the ignition lock cylinder to the RUN position.

Remove the ignition lock cylinder from the lock module assembly by pulling the ignition lock cylinder away from the steering column.

There may be a video on youtube .

May b the ign lock key mech or the contact plate in the sterinwheel..that is a connection for many items. First test batt for 12.6v. Inspect alternator and chargin wire if needed

Not being able to turn the steering wheel at all starts at the ignition lock locking the shaft under the steering wheel. Next if that is ok then it indicates a serious problem in the rack and pinion or the flexible joint to the rack/steering box. As this is a safety issue I would put it on a tilt tray and have a accredited steering repair shop investigate the problem. Check the power steering pump drive belt is still intact

Jerk the wheel back and forth while trying to turn the key

You must take the steering wheel apart and tighten the bolts that hold the tilt joint together, a 4 hour job.

try turning the wheel while turning the key you may need to put some muscle behind it. if that does not work try shift the car from park to neutral.

There is a electronic motor that is attacked to the steering wheel to allow you to adjust it, I would not get involved in that location if you have no working knowledge of the vehicle. The Air Bag wires run up and down the channels near the steering wheel and can cause deployment if you are not careful, take it to a mercedes technician to help you out.

As you move the tilt lever to release the lock pawl from the rack the wheel will move. Yours does not it seems so the rack inside this tilt housing has broken off and has bounded up making the tilt option inoperatble. The steering column will be needed to be torn apart and replace this broken housing with a new one

There is no secret button. It sounds like the linkage between the tilt lever and the tilt mechanism inside the steering column has come loose, or the mechanism is jammed. If that's the case, it's a complicated job to repair it, and because of the air bag in the wheel housing, should only be done by a qualified shop.

When they did the alignment it's possible that they used a tool that locks the steering wheel straight while it's on the alignment rack.If they put too much pressure on the wheel when they used the steering wheel seat lock tool it may have stressed you tilt lock mech causing it not to lock where you want it.Hope this helps