Brand New to QB. I've accidentally made all 300 contacts "inactive". Is there a way to undo this ?

Hi there, @simon-owltech-co.

Thanks for taking a moment to reach out here in the Community. I'd be happy to help you reactivate your contacts.

Can you clarify what contact list you've accidentally made inactive? In QuickBooks Online (QBO), we can reactivate customers, suppliers, or any list elements one by one. I suggest preparing a CSV file or exporting your contact list from Outlook or Gmail. Then, bring it into QuickBooks. Doing this helps you save time. You can check out this article for the detailed steps: Import Customers or Suppliers from Email Contacts to QBO.

If you wish to reactivate them manually, follow these instructions:

1. On the left pane, click Sales or Expenses.
2. Select the Customers or Suppliers tab.
3. Click the Gear icon above the ACTION icon.
4. Put a mark next to Include inactive.
5. Find the customer or supplier and click the Make active link in the ACTION column.

You can also easily manage list elements such as accounts, terms, classes, products, or services.

Please know that I'm just a post away if you have any other questions while working with QuickBooks. I'll be happy to help you out. Wishing you and your business success.