Renaming an extension is trivially easy, but is very unlikely to solve the issue - you need to convert it from one format to another (most likely) in order to open it. Linux systems have a very good utility called file
that can (mostly) detect the structure of an unknown file extension, such that you can change the extension accordingly. A quick Google indicates that a .FILE file is an unknown extension that has it appended to it by Windows - if you think its a .doc then change the file extension and try it out. Make sure you have extensions enabled, click the file, and hit F2
to change the filename and extension. This can also be done easily in command line by simple renaming it (say, on windows, use ren
, or mv
on linux [which moves it to a file of a different name, same functionality really]).
There exist many services online to convert a true .doc to a .pdf if needed, and vice versa too. If you need to edit documents but don't have the Microsoft Office suite of programs, consider OpenOffice or LibreOffice instead - they are free alternatives. Adobe Acrobat Pro can edit .PDF files, but this is not free and I would not recommend doing so unless you are changing a few characters only - better to change the source doc file and then re-export to PDF.
Edit: Since you probably use Windows, there may be a utility similar to file
on linux/unix systems that you can use - whether command line or graphical, it can help you out on what the extension might/should be.