PSM,

You may need a new clutch slave cylinder. Its under the car, up under the transmission on the passenger's side (assuming your 190d is similar to my 190e). The clutch and brake systems on your car use a shared resivoir, so once you replace the slave cylinder you can bleed the system by using the brake pedal. Check out a chilton's manual, or buy a benz manual for 20 bucks on CD. Parts can and should be purchased through the 'buy parts' link on this site, and you can use the search function to look for more info on this job.

One more thing-consider replacing the rubber transmission mount if the brake/clutch fluid has leaked down on it.

cheers,
dan r.