In the list of "Inactive" A/Bs, find the A/B you're trying to look up data for.
Set the A/B as active. Don't worry, this will not re-enable the test for any users.
In the list of active A/Bs, select the A/B.
Click "Build Report".
Refresh until your data loads.
Save your data to a doc or take a screenshot!
Set the A/B as inactive again by choosing a winner in the A/B (doesn't matter which one, but if you remember which group was the winner please use that one)