There are four ways to hide a file in Mac OS X Finder.

1. It hides files that begin with .Fix: rename the file

2. If there is a .hidden file in a directory, it hides all the files in that directory that are listed in .hidden

Fix: remove the file’s name from .hidden

3. It has the hidden flag set.

Solution: (in the terminal) chflags nohidden /Path/to/file