ML320 tail light
 

How do I remove lens to replace blown bulb?
Thanks in advance.

Light bulb replacement
 

Light bulbs are pretty easy to replace. For reference, it's listed in the owners manual in the "practical hints" section, or if you have an older ML with the gray owners manual (not in a binder format) it's in the index under "replacing bulbs".
There are 2 plastic nuts that hold the tail lamp in place. They are located between the tail lamp assembly and the tailgate weatherstrip. The nuts are slotted for a screwdriver, or a 10mm socket will work, whichever is handy. Remove the 2 nuts, then you need to pull back on the tail light assembly, as there is a snap that hold the tail light in place also.
After that, there is an electrical connector that needs to be removed, that's pretty simple. The bulbs are located on the inside of the lamp assembly in the "racetrack" shaped holder. There is a clip on each side of the holder, just press these clips in towards each other to release the holder.
Gilly