Mistake moving catalog

I am upgrading my computer. I backed up my catalog by copying it onto a flash drive and have transferred my image files to the new computer. I accidentally opened the catalog file from my flash drive, rather than copying it to the new computer first before opening it in Lightroom. When I remove the flash drive, it makes Lightroom crash.

I have copied it to the C Drive where the newly created catalog is, but when I try to open it via Lightroom I can't get it to open. When I click the previews folder, it opens the subfolders, but won't allow me to open it as acatalog. I tried uninstalling and reinstalling Lightroom and then copying from the folder, rather than opening the newly  created catalog, but that isn't working either. Help!

I still have the catalog on my old computer and can recopy or export it, if needed.