Corrupt lrcat AND backups! Any ideas how to retrieve/repair them?

Question

Hello, I've painted myself into a corner but hope someone has ideas on how to try to retrieve a corrupt lrcat file. My lrcat file AND its backup are BOTH corrupt, and will not open. They are visible. I have an iMac, OS 10.6, LR 3.3, just upgraded to 3.5 today when I started having trouble accessing LR. I've been away for 6 weeks, but the rest of the computer works fine. There have been almost no changes/writes done to the HD since my last LR backup (and idiotic deletion of additional b.u. catalogs that were only a couple of months old. A trial version of Data Rescue II found erased files on my HD from years ago but it does not find those older LR b.u. erased files.) I am using my laptop for the time being, in the vain hope that a rescue of the lrcat corrupt files might be possible.
There were 20,000 images referenced in LR. Just now I saw the suggestion that large deletions/additions to the catalog should have a "check integrity" cycle done. I have done that cycle sporadically.  Suggestions about how it helps to know the software before using it may help others now.
Thanks.

Answer 1

Hi Hal,
sorry I didn't notice your post earlier. The difficulties with opening LR itself or any catalog have been increasingly worse. At first it was just something along the lines of "can not find the catalog". The first few times I did the click on the catalog routine, LR would try to import the catalog, but become stuck about 1/3 or 1/4 of the way through. It was not an old-fashioned "hang", as LR itself was not showing as "application not responding" in the Force Quit menu, but even after a couple of hours left like that, there was no further progress.
Now LR will not even open. For a while it would open but show only minimal choices in the top of the computer screen menu bar  File  and only three more choices NOT including library, photo or metadata (well, those were not available without a catalog . . . ).
I have tried loading the original catalog as well as the SIGH one existing b.u. copy of that. There are older catalogs, embarrassingly older, but they are more of a misfit with LR. (I've done extensive file rearranging and reconnecting over the summer. More signs of blind blunderings.)
Again, thanks for your reply. I do have dinner guests over now, so I will check back again in an hour or so. Ciao, C Johnson