How to retrieve deleted files from the internal memory

I have a Samsung SGH-A867 Eternity cell phone. While using just the phone in an attempt to move an important video file from the internal memory to the external memory, it appears that I've accidentally deleted the file from the phone altogether. I've attempted to recover the files from the external memory card which is very easy for me to search through Windows, but I cannot seem to use Windows or any other external source to do a file recovery on the internal memory.  I've already manually searched the internal memory to find the file just in case I moved the file to another place in the internal memory, and am still coming up with nada.

Would someone please help me out with this?