How do I add back transactions that are missing from QB?

Hello lrrnfin

Welcome to the Community

Are these bank transactions?

If so you can either upload an excel file(also known as a CSV) with the transactions in and upload them into QuickBooks via the banking section

Or you can manually enter transactions 

If you would prefer to do the latter reply back here with what kind of transactions they are (for example, sales receipt, expense, bill) and we can go through how to add them in

Emma