asd to txt conversion is most likely related to attempts to recover old MS Word auto-backup documents (.asd). These can probably be only recovered using those older versions of Word, thus up to version 2007. Once recovered, you can save the document in various formats, including plain text.
Without the proper version of Word, it will be very hard or perhaps impossible to recover and convert documents from the .asd backup.Open ASD file Open TXT file
One of the most popular word processor program from Microsoft Office suite