I can't open Lightroom anymore, saying there's a problem with the catalog. That could be normal because the main catalog is missing - I only found a Lightroom Catalog.lrcat-journal at that location.
When I try to choose another (backup) catalog, he doesn't accept it. Keeps the main catalog in the window. I just updated Lightroom and had a computer crash while LR was open... I allready deleted the lockfile - nothing.
Please take a look at the solutions documented here Lightroom catalog cannot be opened and let us know if they help to fix this issue.
Also, mention the version of Lightroom you're using.
thanks for your answer but in the meantime the problem was solved. I completely deinstalled Lightroom, restarted my computer and than reinstalled LR. Magic! Everything works like it is supposed to :-)