Missing file types for exporting

[Pebblebrook]

I'me working with Inventor LT 2013 from the AutoCAD/Inventor LT suite.

Been using it for about a year with no problems of this kind.  I have suddenly "lost" all my file types for exporting.  I thought a week ago I saw a post like this in this forum, and read that the fix was to reinstall the program.  I have done this, but it has not helped.  Additionally, I now cannot find the original post by using the search in this forum.

So hears the nature of the problem...

* Completed a design and wanted to export to a .stp file to send off for prototyping.

* Clicked EXPORT >> CAD Format

* By selecting the SAVE AS TPE drop down, the only two file types to export to are .xgl and .zgl, of which I have never used...and there are no other options (no ..stp, .igs, etc.)

How could reinstalling the entire program not fix this?  And how do I get them back, as it puts a complete stand still on my project.

Any help?  Thanks.