The below is the trick for getting back deleted message in ur phone.. the trick will work only on s60 version phones :

A SMS once deleted can’t be read again….but sometimes we hurrily delete some important SMS Here is the technique that must be followed to retrieve deleted SMS Required utility:    1) Any system explorer or file explorer program (eg. fileman or fexplorer.provided with the package) 1) Open Fexplorer 2) Select drive C: or D: depending on the memory in which the Sms messages have been saved. 3) For example u selected c: , Then open “system” folder. 4) Then in “system” folder open “mail” folder. 5) Then in this folder u will see different folders (eg 0010001_s) and certain files (eg 00100000). These files are the actual messages. Browse through every folder and open all files till u get the sms u are looking for. 6) For opening the files don’t choose options>file>open as it will show format not supported rather choose options>file>hex/text viewer. By selecting the “Hex/ text viewer” u ll be able to open and read the deleted