Well if I had done it on purpose I would expect that kind of reply,

The issue being that the complete lack of documentation let alone a read me file that made sense means that many of us are iin the dark when it comes to upgrades.  I was trying to see if I could run two separate portals on the same machine but with different versions of DNN - so I could test that the 4.5.1 version worked for me (because 4.4 did not).  As I stated, the implications of doing that meant that the original DNN database got upgraded even though it was not the database for the second installation, but it was on the same server, on the same partition, and was also a subdomain of the main one.  All in all a recipe for disaster which I am using a wet weekend to try to get around.

Lesson - play around on a development server rather than the production one. 

backup is more appropriate.  Serves me right, the backups for my database were set to fire twice a day and over write the previous backup .. by the time I noticed, another backup had run.

Meanwhile, the rain has kept me indoors with nothing else to do but put it all back together.