Images in collections but not in date-based folders.

I have tried to import the images from the C: Drive to My catalog but it says they are already imported.

Then don't import the photos again. Find them in the Library Module.

Follow all four of these steps in order:

1. In the Lightroom Classic Library Module, on the left, under Catalog, click on All Photographs
2. Turn off all filters (Ctrl-L once or twice)
3. Turn off all stacking (Photo->Stacking->Expand All Stacks)
4. Search for at least one of these photos by file name using the Lightroom Classic Filter Bar

I had an older catalog on my C: drive. No longer available. My images are on an EHD. 

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By @ilab7969133

Does this mean that the catalog doesn't exists anymore?

EHD -> external harddrive??

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I can see the images in collections on EHD but not in the date-based folders.

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By @ilab7969133

That's a little bit confusing. You can't have collection on hard drives. Collection exists only in LR catalog. On drives you have folders.

Please describe more detailed what'e the issue. If possible post screenshot(s) that shows the problem.

Which version of Lightroom do you have installed?