Tackling account access problems after an OS X update
While rare, sometimes after updating OS X either with an upgrade or with an intermediate patch users have found that an account on the system may no longer be accessible. This may be because the system refuses to accept an account password, or because the account no longer appears. While such problems may have you initially consider reinstalling OS X and restoring from a backup, you may be able to fix the problem without doing this.
Missing accounts after an update Local account information is stored in the system's directory database (located in the hidden /var/db/local/ folder), … Read more