All chat messages that your character sends and receives are stored in a text file which is continuously added to by the game client. The name will be something like YourCharacter_Name.txt, and it should be located in either a folder called "logs" in the Planeshift directory, or somewhere in the Planeshift folder in your application data folder.
Search your hard drive for files containing the name of your character, and it should come up in the results.