I reviewed all transactions but had to reconnect to bank. I did this but lost all reviewed transactions and have to start again. even though its saying they've been reviewed!! Help

Hello there, alanstonerest-ya.

In QuickBooks Self-Employed, once a bank account is disconnected, all transaction history will be deleted permanently. That's the reason why you've lost all the reviewed data. What we can do is to categorise the transactions again.

Creating rules in the program helps you speed up the process of reviewing them. You can check this article for the complete steps and details: Learn how to create and use rules to quickly categorize recent and past transactions. 

Also, you may want to check these articles for more details about keeping transactions organize in QBSE:

• Categorise transactions. 
• Learn how to split a single transaction between business and personal, or into multiple categories. 

Please let me  know if you have other concerns. Stay safe always.