Product/Service assigned to this transaction has been deleted.

Thank you for posting in the Community. I'd be happy to help get this taken care of today, @robpm-ps4av-com

You can check your audit log to see who made changes to your books and what they did. This tracks user sign-ins and changes to settings as well as edits to customers, transactions, and employees. 

To access the audit log, you need to sign in as an admin. Then, follow these steps:

1. Click the Gear icon at the top.
2. Choose Audit Log.
3. From the Filter drop-down, choose the appropriate User, Date, and Events filter.
4. Select Apply.
5. Locate the deleted transaction. Tip: To easily find deleted transactions, use the browser search Ctrl + F and type deleted.
6. Under the HISTORY column, select View.
7. All the information needed for the transaction can be found under the EVENT column.

To learn more about the Audit log, check these articles:

• Use the audit log in QuickBooks Online
• How to Use the Audit Log: Finding Errors & Transaction Histories

Once checked, you can create a new item for your Product and Services. Use the information from the Audit Log to re-enter the items.

Here's how:

1. Go to the Sales menu and select the Products and services tab.
2. Click on New and set the type of this Product/Service. 
3. Add all the necessary information. 
4. When you're done, select Save and Close.    

 Here's a guide on how to add a new product or service item: Add product and service items to QuickBooks Online.

In case you need to track your best sellers or the total sales for each product or service, you can utilize reports to see your sales and inventory status. With the help of the reports, you can easily track your items in QuickBooks Online.

These resources should help to get you on the right track, @robpm-ps4av-com. Feel free to hit the Reply button if you have any other questions. I'll be happy to help you further.