[SOLVED] My terrain... it's gone, and I'm in panic mode

Ok, let me get this out of the way now:

HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!

Sorry. I'm panicking like a turkey on Thanksgiving eve.

So here's the deal: Have been working on my project for a few months now, and a buddy turned me on to an assets site that included a character creator. Upon importing it, however, my terrain disappeared in scene and game view. Still appears in the hierarchy, but is completely transparent. I emailed the admin of the site I purchased the asset from, his answer on how to solve this was as follows:

Very very interesting and I know why - the project is supplied with a demo scene showcasing the OBM characters, which stand on a blank terrain - that's probably why its overwriting your one. Maybe rename your original terrain? Or I could update the pack so the characters are not standing on a terrain, and just a large box - the terrain servers no purpose to be honest, just a platform for them to stand on.

But I'm not sure as to next steps, and his next response was "hope you had a backup." (which I do) But before I go that route, I want to see if my project, which has about a day's worth of work more than the backup is salvageable. I tried his suggestion of renaming the terrain, no dice, and even tried deleting his demo. Also no dice. Am wondering if anyone knows a solution to this beyond what I've tried before I hang my head in shame and go from my backup. Thanks, and God bless.

Mark

P.S. Happy Thanksgiving to my U.S. friends!