Hi,
You can try to get the special changeset and modify the file and then check in.
You also can use the team foundation power tool "tfpt" and do "tfpt rollback" to rollback.
For more information, see http://blogs.msdn.com/buckh/archive/2005/11/16/493401.aspx.
You also can ask this question on the TFS forum, which has many TFS experts.
I hope this helps.
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