[The Sims Medieval] I lost code for game I have used it before but it was erased from computer

Don't you have the game disc and manual with the code anymore?

Did you perhaps at one point register your game on the Sims website? If yes you can always download it from Origin. Just log into the Origin client with the same email and password that you use for the Sims website.

You can get the Origin client here:

http://www.origin.com/download