Sheila,

You probably do have the foot pump on the floor; it's waaaay up high on the left side, possibly covered by the carpet. It's a little hinged metal plate with a bumpy surface. In typical Mercedes fashion, it not only squirts the windscreen, it also turns on the wipers!

However, this information alone may not be enough. My 240 squiter has other problems, like plugged-up lines from crud in the reservoir, and broken check valves that make the system function. Check these items out if the pedal doesn't make things go.