the data was not complete, or
B: it was an error on our part.
In most cases, A is the reason why registrations were rejected. A rejected registration cannot be restored because all data of the registration has been deleted. The only thing left to do is to register again.
If it is B, i.e. an error on our part, then we can no longer change anything for the above reasons (the data have been irretrievably deleted). Mistakes are human and can happen. In this case, I apologise - and ask you to register again.