One of those threads where 5 mins on the OP's PC would solve the issue quickly, but trying to explain it on a forum requires the patience of a saint
1. Find the file extension (.doc .docx .txt)
2. If MS Word and notepad won't open them, then highly likely you have corruption
3. Save originals and try changing extensions to .txt , then try notepad again
4. Save the documents again from original source to a known good working USB stick, paying particular attention to the program and version of the original software. If a later version of word then don't accept the default , instead save as .doc file so older versions of word are able to open the document, all be it with some small differences in formatting.