there is no software that can convert a PDF to aTXF
TXF is a specially formatted text format for accounting / tax purposes. It is unlikely you can directly convert pdf files to TXF format, but in case the PDF file is just a print of opened .txf file you could simply copy it back, save it as text file and rename the suffix from txt to txf. But you certainly cannot do that with just any PDF document.
Generally speaking, any program that can import or open PDF documents can save them in a common text file, except in cases when the PDF's are locked and rights for text copy is restricted.
You can also manually copy and paste the text from opened PDF to Notepad or other text editor / word processor, provided the PDF file is not locked for text copy.
