Have had the computer new for a few days, was all working fine. I edited a gallery on it & now I can not open lightroom C at all, I have forec quit, reinstalled & still no joy, Mac operating on Big Sur, help me please.
That could/would have resulted in LrC not cLosing properly, resulting in the lock file not being removed. The lick file is created when you open a catalog, it is deleted when you close LrC. Purpose is to prevent multiple instances of LrC running using the same catalog.
Bigger question is why were you forced to force quit.