This video teaches you how to fix the "Login Keychain" error in OS X Yosemite 10.10 & OS X Mavericks 10.9. This is a common error that usually occurs if you've forgotten your login/administrator password to your Mac user account and/or have changed your user account password. Keep in mind, this does not apply to earlier versions of OS X. I will be making a separate video on how to fix this error in previous versions of OS X.
This step-by-step tutorial is also available on Apple's PUBLIC support website: https://support.apple.com/en-us/HT203897