if I have an external drive, and Lightroom can't find my photos, and I transferred all of my photos to my external drive, if I rename the external drive can Lightroom not locate those photos?
You'll have to right-click on the folders and choose the option to update the folder location in order to show Lightroom where the images are now located. Once you do that then Lightroom will display the images with the adjustments. If the images are all organized within one master folder then all you have to do is update the location of the topmost folder. Everything else will fall into place.