Find photos

If you click on the exclamation mark, then Lightroom will show a dialog telling you where the image should be (but isn't). What does it say? Does it perhaps refer to an external disk that is currently not available?

Did you follow these instructions (or similar)?

Can you find the photo files using Windows Explorer? Are they in the exact folder where LrC expects them to be? Are they named the exact way LrC expects them to be named? What is the exact folder path and name? What is the exact file name and extension?

I have even had an Adobe employee take over my computer and he could not find them either.

Do you mean he could not find them using the Windows Explorer search feature? Did you (or he) use Windows Explorer to search all disk(s) and all folders for files with the exact name that LrC shows?

The most likely conclusion is that they are gone, and should be restored from backups. Could also be that they have been (accidentally?) renamed in Windows Explorer and this makes them tough to find. Again, restoring photos from backups would be a good thing to try.