Reading attached files

[praarp]

My computer can read .pdf files, and opens .doc files with something called craftydoc
But it fails to read a .txt

 

[davehc]

I have no knowledge of Craftydoc, but I would suggest you use a more comprehensive (and Free) document program, there are many available) .
But, Open the Control panel - Default programs, and assign all the documents to craftydoc., and see if that works.
Windows 10 should, though, by default, be opening your *.txt files with the built in program "notepad", unless craftydoc has corrupted the path in any way.