Where have all my customers and suppliers gone from the app??!

Welcome to Community, @richard35.

I have some information about your customers and suppliers. This could be an app interruption. You'll want to clear the Window App's Cache to refresh your account. This way, you'll be able to see your customers and suppliers info.

Here's how:

1. In your QBO app, go to Help.
2. Choose Reset App Data.

After resetting, open the app and be sure to run as administrator. Then, go back and check your customers and suppliers again. Want more details? Check out this guide: QuickBooks App for Windows and Mac.

In case you need help with other task in QBO, you can browse a specific topic here and look for the one that suits your needs.

Let me know if you still have questions and concerns. I'll get back to you the soonest. Take care and have a good one.