I had the same problem in the last months.
It happened with 5 OE.
The OEs "pending for approval" are still there and available for you, because you know their http.
But no one can find them in the database.
Follow gogar �s advise and edit them again.
Edit the exercise "pending approval"and save it.
Then open a new OE and open the saved file.
In this way you don �t have to make the OE again.
If the OE is approved, in your "My printables" list you will have the new and the pending OEs.