I did this last time (last year), some combination of key in ignition and pressing and holding trip button on dash.
Does anyone know what combination it is?

I'm assuming you have an older C-class (202 version).

Turn the ignition key to the "on" position. Double-click the reset button (your service interval should appear), turn the key off, hold the reset button, and turn the ignition back to the "on" position while still holding the reset button. Wait a couple seconds and it should reset.

Note, some vehicles require you to have the driver door shut.

Thanks for that worked fine.

Finally I was able to reset. Thanks for your help.

A question: while messing around with the buttons a date came up, how do I get that back and can I reset that too ????

I cant get this to work right and neither can my mechanic what are we doing wrong ?

I cant get this to work right and neither can my mechanic what are we doing wrong ?
The date thing comes up but the counter doesn't reset

This is the method specified in the operators manual that came with my 2000-C230K 4Dr. and I could not get it to work either. Anybody know the secret?