Matt - you just delete the report (you need to go File > Open in the Report Designer, selected it and then click Delete), and then copy the standard estimate screen from the Method Library you should get the report back (it will see it is missing and then add it for you). Tip: in Step 3 of the Copy/Import don't add any tab links.
If that doesn't do it, we do have a utility that we can run that will restore it for you.
Paul