I had quite a few Collections set up in Lightroom but now I can only find one. I have tried right clicking and choosing Show All - doesn't fix the problem. At the same time, the number of All Photographs under Catalog has reduced dramatically, probably now just reflecting the number of photos in the collection I can find - not sure if this is the case but the number of photos in All Photographs is significantly less than before. I would very much appreciate advice on how to find the missing collections.
You've opened an older or alternative catalog that does not contain your collections. Collections don't just disappear, at least not for me since I started using them some 7+ years ago through at least 4 different versions of LR
Thanks for your response, but I'm still at a loss. How do I find the right catalogue? I'm sure too that collections don't disappear but I'm not sure what I did to open the older or alternative catalog, or how to find the correct catalog.
OK, think I have it now. I opened a new catalog to upgrade, when I should have upgraded my old catalog. Thanks very much for your help.