Lost catalogs after Lightroom 5.6 update

I reluctantly updated Lightroom 5.5 to 5.6 last night and the next time I tried to reopen Lightroom my most recent catalogs were gone.  My iMac opened Lightroom with catalogs from a year ago.  All of my most recent edited catalogs are MIA.  The same thing happened the last time I did the update and I never did find the photos.  I have tried relaunching in different versions, using Time Machine to back-up to a day before the upgrade but nothing has retrieved my most recent Lightroom set-up.  Please help.