I updated from Snow Leopard to Yosemite yesterday. I have never updated my Macbook since I got it in 2012 because I find that updating OSes typically just causes problems. I don't always like being proven right. I had two user accounts on my MacBook prior to updating, and the non-admin one is no longer there on the login screen, nor in the Users folder, nor in the System Preferences' Accounts page. I Spotlighted the name of the account and some of the files that were on it to no results. I tried creating an account with the same name and it did not offer to restore the old account. I had hundreds of GBs stored in that account. I would like to have them back. If anyone has any ideas of how to do this, I would appreciate their help.