Is this somehow possible that i convert these games on symbian os.
Because i would really love to play those games on my n-gage
To be able to play the games made in AGS on other OS, an interpreter (the engine) specified for that particular OS has to be built. There are currently three AGS engines available: for DOS, Windows and Linux. I had no experience with the OS you have mentioned so I can't say how difficult (if at all possible without rewriting the large amount of code) it would be to build one.
http://www.agsforums.com/yabb/index.php?topic=10910.0