is it possible to retrieve a conversation that i deleted?
thanks..

not unless you have a back up i'm afraid

well i did but i deleted them too lol....

Technically things aren't really deleted so much as removed from the index which tracks where things are. Unfortunately, you'd need a tool that can find that piece of data and bring it back, of which I know of none available on the N900 (or any phone for that matter.)

lol here too

How about mounting the filesystem that the conversations are stored on, over SSH, to a computer and using restoration tools from that end?

If I'm not mistaken, conversations are stored in a SQLite-data base:
/user/home/.rtcom-eventlogger/el-v1.db (PR 1.2)
so my guess is you're out of luck. Sorry.

for videos or pictures you can use any disk rescue desktop program.
i accindentally ereased all pics from my holidays in poland but i resued them with a winxp app called diskdigger.
it takes some time but you can rescue most files.

Perhaps if the database was not compacted since you have deleted your conversation you could try to copy the database to your PC and try to find your conversation using a Textviewer. You are still unable to restore the message, but you could read it and write it down on a piece of paper.

Perhaps look at you old backup. Open the comm_and_cal.zip, search for Root\home\user\.rtcom-eventlogger\backup.tgz extract from there el-v1.db and have a look at the content of this file using a File viewer (text or Binary Mode)

Please report if it has worked.