Hey - my past invoices seem to have disappeared from my account. I've used Quickbooks for the past 4 years - does anyone know if this is an error or how to get them back?

I can help you locate those missing invoices, digitalbec.

First, try to check the filter you set from the Invoices page. 

Here's how:

1. From the Sales menu, go to the Invoices tab.
2. Set the Status to All and then the Date to that specific date range. 

If still missing, try to check your Audit Log. It'll let you see the any changes made to that specific invoice. Also, it'll show you the original transaction date and amount, the date, and the name of the user who made the change. 

Here's how: 

1. Go to Gear icon (⚙) and select Audit log.
2. Select Filter.
3. Use the fields on the Filter panel to choose the appropriate User, Date, or Events filter to narrow the results.
4. Click on Apply.

Check this article for more information: Use the audit log in QuickBooks Online. 

From here, you can use the audit log to re-enter deleted transactions. 

Let me know if you need further help looking for the missing invoice. I'm always here to answer them for you. Have a wonderful day!