I created a text file, saved it and then deleted it to the Recycle bin, and emptied the recycle bin. Then immediately, without doing anything else, I used Recuva to try to recover the text file but it will not find it. I had another text file that was deleted with Shift Delete, yesterday and it could not find that either. I tried searching document files, but noticed that the designers did not include text (.txt) files in documents. I also tried searching all files. It finds other things deleted but not any text files. I enabled deep search and it still did not find any text files including the one I just deleted.
Recuva does find deleted txt files during a normal scan. It's quite usual not to find a file that has just been created and then deleted. Opening Recuva writes a file to the c drive, then there is prefetch and various other Windowsy things going off. The recycler also renames deleted files.
It's best to open Recuva, run a normal scan, create and shift/del your text file, then scan again. You should see your deleted file. Or just enter .txt in the File/Path box to see what you have.
Txt (and bat) files can't be found with a deep scan as they have no file signature, they're just blocks of text.