I urgently need an application software that can convert mobile phone short messages into txt. My mobile phone is Nokia 5320xm.

Hehe, you can use pc suite to link computers, and then back up short messages, which will become txt format. If you must use mobile phone application software, you can install SmartFileMan file manager. The specific method is probably like this: save the short message to be turned into a txt file in MMS format in the draft box (method: click Send in the short message saved in Notepad, select the MMS being sent, and click Close directly after loading). Then open the installed SmartFileMan file manager and click "SMS Inbox" to find the file with suffix. Txt is in it, copy it to the folder you want to save on disk E or disk C, and finally delete the MMS in the draft. This multimedia message won't be sent out, so it doesn't cost money. Haha's laughter ...