My computer (PC) crashed when I was in Lightroom yesterday and after doing a hard shut down of my computer, I reopened Lightroom to read the following message: "The Lightroom catalog named "Lightroom 5 Catalog" cannot be opened because another application has it opened." I clicked "Continue" and Relaunch, but it won't let me do anything. I already tried restarting my computer multiple times and doing "Task Manager" but cannot find it open anywhere else on the computer. Help please and thank you!
Go to the folder where you Lightroom catalog file is located (this is a file whose name ends with .LRCAT)
In that folder is a file whose name ends with .LOCK (might be lower case). Delete the .LOCK file. Do not delete anything else.