I switched laptops and imported my photo folders and imported them to my new Lightroom mobile. I then deleted those original photos. Now my catalogs say that my photos are missing. Do all the original photo files need to be on my desktop still in order to work with Lightroom? Luckily I still have them on a hard drive...
Yes. Lightroom must have access to the original images. (Internal Drive, Connected External Drive)
Hopefully you can copy them from the 'other' hard-drive in the same folder location and structure as in your catalog.
See "Missing Folders" in this document- How to create and manage folders in Photoshop Lightroom