When LR is running, a .lock file is created in the same folder as the catalog to prevent other users to access the catalog. The .lock file is normally deleted when you close LR, but if the program crashes, or if there is a power failure, it will not be deleted, and you get the error message you mentioned.
Make sure Lightroom is not running.
With Windows Explorer, go to the folder containing your catalog, and delete the .lock file.
Do not delete anything else.
Now double-click the catalog (.lrcat) to launch LR.
Since you were able to launch LR, you must have several catalogs, so you have to find the folder with the catalog you want to use.
(using more than one catalog is normally unnecessary, and not recommended)
Thank you so much for your answer Per Berntsen. I did delete the the .lock file, I found two of them! This is what my folder looks like...??? I bought a new computer last April and they transferred the files and then I had someone else work on the computer when I had a problem with LR afterwards. Can't say I have ever opened the LR folder. I am now able to open LR from my start menu but it was still missing the the past year and most of the files are missing (image below). Would I be correct in that I could replace those files just by finding them on my HD and importing? At least my Collections are there, which is important. When I attempted to open LR from the LR folder (choose the one with the most MB thinking that would be all the images) I was asked if I wanted to upgrade to LR 6 and which catalog (image below). Also, should I deleted all these other Catalogs? I know this is a crazy mess and thank you for any information! I am beyond lost!
If the problem is that there's a year of photos with exclamation point icons, then importing will not help, it will make things worse, it is completely the wrong thing to do.
The instructions for fixing the exclamation point problem are here: Adobe Lightroom - Find moved or missing files and folders
But I'm wondering if you are opening the proper catalog file. If you use your operating system to search for files whose name ends with .LRCAT, and you double-click on each one to open it in Lightroom, do you find a catalog where the photos are not missing?
Thank you dj_palge,
I am missing the last year of photos and the ones that are there are from years past, most have the ! mark by them. Thank you for the information on finding the files. Before I read your information, I did a right click on the folders missing and found them that way and it seemed to work. ???
I did a search, just opened the search for programs/files and typed in .LRCAT and nothing appeared. I am not computer savy, so hoping I did this correctly. I have no idea if I am opening the proper catalog file. Should I delete the LR 3? And if I find the correct one, delete the others? That just deletes the catalog file but not my pictures, correct?
I should also say that I have a separate hard drive for keeping my photos on and those are the ones that are missing I just discovered, but I am able to find through the right click method. The ones that are not appearing are the ones on my C drive.
The article I linked to also talks about right-clicking on the folders to fix this type of problem.
Yes, you did the search properly.
I have no idea what is in the LR 3 catalog, so I offer no opinion on whether or not you should delete it or not. You have to open it and look at the contents and then decide if you can delete it or not.
I just took a chance, opened up the catalog with the most MB, updated the older catalog...and there everything is! WOW!
When I opened up the LR 3, it was empty and I needed to import? So now that all my images are where they should be,would I be safe to delete that catalog and would I also be safe to delete all the others that for some reason are in that file? I would like to get this cleaned up so this doesn't happen again.
Yes, now that you told me what was in the LR 3 catalog, it seems to me to be safe to delete.
would I also be safe to delete all the others that for some reason are in that file?
Same answer is before. You have to look at each catalog and decide if you still need it.