My first question how did your web designer accidentally redirect the entire site what a blunder. 2nd question is has this been undone as from your post they are still being redirected? 3rd question are both sites the same content?
If the sites are different content then just undo the redirect and give it some time.
Time is a great healer ... provided the designer didn't panic and do something silly to 'compensate' for the error, a couple of Google cycles should see the status quo re-established. Days on a large, busy site, maybe longer for a smaller, quieter operation.