I need help, for fixing my 92' 300E, the interior mirror is lossen, how can I remove it and are there any method to re-tighten it??

There is a fitting inside of the mirror body. It is a ball and socket arrangement. The breakaway fitting rarely gets loose. The socket which the stalk goes into can get loose inside of the mirror. Disassembly of a mirror itself can be tricky. The housing snaps into the glass frame and can easily be broken when disassembling. Some models have little screws as well. I think yours is a one piece housing. Two choices, get used to it as long as the mirror stays where you put it, replace it or try and fix it. Whoops three choices.

this is not easy, you have to break it!!! dont worry it won't be permanent. first, pull the whole mount out of the roof of the car(evenly!)the screws mounted in it you can't get there from here. second, depress the spring in the whole assembally and remove the pins in the roof assembally. third, you can mount the roof assembally with original screws. ( if those screws are too loose use lager sheet metal screws.) forth, replace the spring and pins in the mirror assembally and add a little wd40 and it will slide right in easier than it looks. ( i've done this in the dark once) these mirrors are only supposed to be installed once but it can be done.
feel free to e-mail me if you have any questions.
good luck!
adam