A tool that does this is called a "decompiler". As far as I know, in practical terms, especially if the object file was produced by an optimizing compiler or the -g compiler was not used, there is no such tool.
The best you might hope to achieve is to convert it to assembly code and as that is rather platform-dependent, you would have to figure out from that code what is really going on. It would be much easier to reprogram the thing if you know what it is meant to do.
An alternative question might be can you convert the Fortran Linux built .o file into a compatible Fortran Windows build .obj file. It might be possible to do this, but you may need to add helper functions if the calling conventions differ. Other than that, it is reverse engineering from the assembly code.
