Can anyone tell me how to revert (roll back) a checkin in TFS 2010?
There is no undo option in TFS (up untill 2008, I haven't used 2010 yet). There are some command line power tools you can use to rollback changes that may help:
http://msdn.microsoft.com/en-us/library/ms194956%28VS.80%29.aspx
HTH
You can rollback a changeset (in TFS2010) through command line doing:
C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\tf.exe" rollback /changeset:123 /recursive
Note: you must use tf.exe full path even in Visual Studio Command Prompt to avoid "Unable to determine the workspace" error. More info here
Rollback reference (TFS 2010)
https://msdn.microsoft.com/en-us/library/dd380776(v=vs.100).aspx
For 2010, use the rollback command from the command line. There is not integrated support in the IDE for this, as of yet.
Rollback command
Basically, the way that it works is that it creates an "anti-delta" to negate the impacted changeset. You can accomplish the same thing manually by doing a Get Specific Version, adding a space to the file so it looks like it changed, and checking it in. I still go the latter route to back out a change if I need to for a single file, as I find it quicker to do.
Without using power tools or command line:
Rolling back changes for another user
If you are attempting to rollback changes for another user, make sure you get latest on the files you are attempting to rollback; otherwise you will see the error:
"No changes to roll back."
right click file in Visual Studio and Source Control/View History then select last changeset, right click and click Rollback After rollback done, you should check in again.