|Then there was something wrong with what you put in the file. Here are some possibilities.|
The first line should be:
Windows Registry Editor Verision 5.00
(usually followed by a Return - line feed)
There should be an end ] (for each line). Go back to wherever you got this info. See what it says and compare it with your reg file. You can view your .reg file by right clicking it and selecting Edit.
Note also that there should either be one or two returns (line feeds) at the end of the file - no more, no less.
Your reg file will only do the right thing if it is "exacty" right in every detail.
There are downloads for fixing file associations.
Please come back and let us know the outcome.