Missing a GL entry

When I switched the type of account (Group account to subgroup account) and I save, Sage told me that my debit and credit don't balance anymore and I had to put the balance on my retained earnings account.

Now, my historical opening balance is different of what it should be.

Also, i found that one of my general entry doesn't exist anymore and that the amount of the entry is the reason i don't balance anymore.

What can I do to repair it?