Correct postings following clear invoices in closed year

My debtors showed a balance that was not real after I closed the year. I don’t know how these invoices became listed as unpaid as I had posted all the bank transactions. I clicked on the mark as paid button.
The effect has been to create a debit on the Profit and Loss Account in reserves (no account code) and a credit in my debtors. I want to clear out these balances but the year is closed. I can’t use a journal as the new ‘profit and loss account’ in reserves has no nominal account number.
As a result my balance sheet is nonsense. Is there a way of clearing this out? My plan was to create a journal but would have to create a new reserves account, thus leaving 2 accounts with a matching debit and credit balance.

The balance is sitting under ‘Current Liabilities’, therefore you have client payments posted as payments on account, which have not been allocated to any invoices. If you click the magnifying glass to drill down the to the nominal transactions, you will be able to check the transactions that make up the balance.

I will send you a private message with further information to assist.