All my contacts have disappeared and most of my data.

Greetings! I'm glad to welcome you to the Community forum, Bookings. We appreciate you expressing your concern about your contacts and data have disappeared. I'd be pleased to give you some steps to help you solve your problem. 

Please verify if you've used the accurate company access and check if there are changes in your account by looking at your Audit log.

Additionally, a user can experience unexpected behavior, including runtime errors, in which case we can typically fix the issue via typical browser troubleshooting. 

Let's first sign in to your QBO in a private window. Here are the keyboard shortcuts:

• Safari: Command + Shift + N
• Google Chrome: CTRL + Shift + N
• Mozilla Firefox or Microsoft Edge: CTRL + Shift + P

Once you're in, reopen your QuickBooks Online account. Let's see if you can now see your data. If it's successful, return to your regular browser and clear the cache to start afresh. If the same problem persists, we can try another supported browser. The one you're using may have temporary issues with QuickBooks Online.

You can also visit this article for reference on exporting your QuickBooks Online reports and lists and downloading the data entered into your file to your local hard drive: Export data, reports, lists, and more from QuickBooks Online

Don't hesitate to reach out to us whenever you have additional questions with any QuickBooks-related concerns, Bookings. We always have your back, and I'm ready to help you. Keep safe!