HELP! - Lost half my site definitions

I was doing some hand coding with the PHP/MYSQL server model, which can
cause confusions to DWMX and when I came to shut it down it hung, so I had
to CTL ALT DEL the prog.

On reopening DWMX all my site definitions below the letter K have all gone!

This is no small number of site defintions and I would REALLY appreciate
being told how I might get this issue sorted. I would think some file has
been corrupted??

Any advice glady accepted

TIA