How can I undo a changeset rollback in TFS 2010?

Get the Latest version and Rollback the earlier roll-backed change set and now they get checked out and now check in the changes after required modifications.

You can always "View History" and retrieve a particular Changeset...

If you select "Rollback Entire Changeset" in TFS, it changes the local files so that the changes made in the changeset are reversed.

Since this is a local change and does not take effect until you check the changes in, you can "undo" the rollback by using "Undo pending changes" on your project. Note this will also mean any other uncommitted changes would also be lost, so use with care.