I am here to help you sort this out, @misc-contracting.
Your customer information may have been accidentally deleted. Let's first access your QuickBooks account using a private browser or incognito browser. By doing this, we can isolate this unexpected missing customer information for a possible browser-related.
You can use either of these keyboard shortcuts:
Once logged in, let's try locating your customer information. You can start by viewing the Customer Contact List. It contains the customer's phone number, email, billing address, and other contact info for each customer. Here's how:
If you're able to locate your customer information, you may want to clear the browsing history of your regular web browser. This will remove previously-stored browsing data that might have caused the issue. Otherwise, you can try using other supported browsers to be thorough.
On the other hand, you can view the audit log to check if any changes were made to your customer's information. It allows you to keep track of your activities, where you can see who made changes to your books and what they did. This also includes the time in and time out of the user into the system. Here's how:
If your customer's information or invoices were deleted, you may need to manually re-enter it.
I'm adding these articles as an additional reference on how the Audit log feature works:
Keep me posted if you need a hand with managing your customers and transactions in QuickBooks. I'm always here to ensure your success. Take care always.