Oh jubujoy I am so sorry to read your post.
I am surprised that United does not send an e-mail when points are redeemed - to me it is one of the many failings in their IT system.
These days United no longer posts the itinerary to your account when your miles are used (recent change) - another failing in my mind. Not that this issue would have helped in your particular circumstance.
Good luck and I hope the points get reinstated.