What it is for:
or google search for more info.
You can try to reset the Keychain Database and see if it works or not
- Goto Macintosh HD/Applications/Utilities/ and open Keychain Access
- From the Keychain Access menu, choose Preferences.
- Click Reset My Keychain, which is under the General pane.
- Authenticate with your account login password.
- Quit Keychain Access.
- Restart your computer.
I was suggesting this because the OP said:
"what is Keychain, I never use it, I keep a record of the passwords myself"
So if all entries are lost, he can add them again, because he has them stored elsewhere or written down.
Thought this would be the quickest way to resolve this, just trying to help, nobody else was answering Johns question.
no offence, you probably know more about it than me, given your level. I'll leave it to you.