Theres a couple things you can try, reloading your last saved game;fast traveling;going to the place you found your follower.
I know there was a glitch that happened to me that jzzargo was stuck in a rock and couldnt get out even when i fast traveled. in this case youll just have to reload your last save game before your follower left.
If you suspect your follower got stuck like mine did, go to the place you told him to wait and use aura whisper.
I also had a follower get stuck in some rocks. Fast travel didn't help. Going in and out through doors didn't help. Finally hit her with the Unrelenting Force shout. That jarred her enough to free her from the rocks!