When you change login info or domain of the SharePoint users, like for example, adding a new domain or updating old domain for some reason. Problem is that after this change, old users data would not be accessible because it was refferenced by using outdated domain or login info.
Fear not, as the solution is pretty simple. Just use following STSADM based command to change login info.
stsadm -o migrateuser -oldlogin <domain\name> -newlogin <domain\name>
If you are more adventurous, you can also see "UserInfo" table in the SharePoint content db (after taking backup) and update domain of the users there.
Beware, do that change at your own risk :-)
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