Word files got changed to .txt files

I have a student working on his project at home using Word 97. The files got changed to .txt files. Now the files cannot open by Word. It can open by Notepad but the content becomes garbage ( all circles & symbols etc. ). I tried to rename the file to .doc , but it’s the same when it’s opened by Word. Is there a way to convert the file back to .doc so it can be read by Word ?
This is for a student’s senior project, so any help ASAP is appreciated. Thanks.