By using a backup catalog that is a month old, you will not have any work available that you did in the catalog that is causing the problem. The problem catalog is probably unusable. Do you have more than one hard drive in your computer? Or, do you have USB memory sticks? Make a folder on one of those, preferably a second hard drive. Name the something memorable like "DavidsLRClassicCCCatalog Backup". Then with Lightroom closed, copy the catalog you are currently using to the new folder you created that different hard drive or memory stick. Now that LR is working, go to Help, System Info and see what version of LR you are using. The latest is 7.3.1
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