PE 2021 New Computer Photos On Drive C, No Longer on E

No magical solution in your situation.

Using the option to  reconnect all the files to the new location won't work, even if that is useful for smaller batches where you can guide the search.

So, if you have not used the recommended way to migrate both the media files and the catalogs via full backup and restore to the new destination, what can you do?

- If the old computer is still working, use the backup and restore process. Create a master folder for the destination, preferably directly under your root folder, not the Pictures of Windows.  Or even to a separate external drive.

- If your previous E drive was an external drive or an internal one which you can  use externally in a special USB enclosure, there is hope. The catalog(s) you have already recovered will recognize the necessary data for the paths: the folder structure and paths and the internal serial number of the original E drive. What you'll have to do will be to assign the E letter to that drive in Windows.

- I don't know where you have copied your media files on your C drive, but I suppose you'll never be able to use them now with any catalog, even with editing the sqlite database.