Did you have Referential Integrity indicated for this relationship? If so, how did this happen?
Only solution is to recreate the one side of the relationship with a new record. Do you have the data to do that? How about backups. Get the whole table and select out the record needed and perform an append query.
That doesn't fix your problem with how it happened. Check out the relationship between the two tables and make sure that you have selected the options properly so that if you are going to delete the one side of the relationship then the many has to be deleted also with a prompt.
Only solution is to recreate the one side of the relationship with a new record. Do you have the data to do that? How about backups. Get the whole table and select out the record needed and perform an append query.
That doesn't fix your problem with how it happened. Check out the relationship between the two tables and make sure that you have selected the options properly so that if you are going to delete the one side of the relationship then the many has to be deleted also with a prompt.
Good luck and let me know what you find out.