Teleport your lost companion to you!

On PC: (try the simpler console methods above first)

• Save your game.
  Reload a game where your follower is with you.

• Now open the console with the `/~ key on your keyboard.Click on your follower, and it should display their ID in brackets. For instance, with Erandur it displayed: " (00024280). Write this number down.

• Reload your current game (the one where you're looking for your follower), and open the console again.
  Type in 'prid putfolloweridhere' (selects any object in the game)
  Hit enter.
  Followed by 'moveto player' (moves that object to your location)
  Then hit enter, and they should be moved to you. Close the console again by pressing the `/~ key.
  
  Example: to move Erandur to your location:
  Type: `
  Type: prid 00024280 (enter)
  Type: moveto player (enter)
  Type: `
  Erandur will appear next to you.
  
  Followers moved with this method will still have all their items etc from last time you saw them.

Some follower IDs:

Layla: 000a2c94
Erandur: 00024280

Read more: http://wiki.answers.com/Q/How_to_find_my_follower_in_Skyrim#ixzz1i83VaKP6