photos failed to export

I have a problem. I was in the field all day Saturday and chose to download my photos to Lightroom briefly, then move them to an external hard drive. I reloaded them to Lightroom Sunday to finish. I narrowed down the 1500 photos to 320, and now Lightroom will not export them. This time the message is different from normal issues of just a few failing to export and having to redo them.

this time I get a message that 320 failed to export, folder not found. then 1 to 100, 100-200, 201 to 300, 301 -320, failed to export.

Where are my photos and why can't I export them? i already deleted the originals as part of my "cleanup" and intention to put these final versions into the original file. It won't let me export them to the external hard drive or my computer hard drive. I assume I should not have deleted the originals-that somehow it was editing the originals and not a temporary version of them maybe?

A lot of work is tied up in these photos. Is there any way to export them? They are still pulling up every time I open lightroom so surely the temporary files still exist.

OK. A friend has told me that Lightroom just catalogs folders at the priginal source, doesn't make a copy? So although I see them, they don't exist? no way to retrieve them.