I use an external drive for my photos and import them into Lightroom running off of my mac. I've worked for the past year on key wording every photo for easy searching. Last month I started using a new mac computer and now when I go to Lightroom my photos are no longer there and if I re-import them from the external drive, the key wording is gone. Are my key words gone or is there a way to find them?
You need to transfer the same Catalog on which you worked for the past year from your previous machine to the new one.
Refer this tutorial to transfer the catalog : How to Migrate LR to Another Computer | The Complete Picture with Julieanne Kost | Adobe TV
If you still have the old computer available, follow these instructions: http://www.lightroomqueen.com/how-move-lightroom-to-new-computer/
If you don't have the old computer available, you would need to have saved the catalog file (or a backup) from that computer somewhere. If you have that, you can double-click on it to open it in Lightroom, your keywords will be in there, you will have to reconnect the photos in Lightroom via http://www.computer-darkroom.com/lr2_find_folder/find-folder.htm
If you don't have the catalog file from the old computer (or a backup) from the old computer, I think your keywords (and edits and other user-supplied metadata) are gone.