Thank you for posting here in the Community. I can help you access your invoices in QuickBooks Online.
If you're using a web browser to access the product, the stored cache may be full. It can cause unusual behavior in QuickBooks Online (QBO), such as not being unable to access invoices.
I'd first suggest logging into your account using a private browser. This process allows you to access sites without storing any data in the cache. Thus, it's a great way to isolate browser-related issues.
Use these keyboard shortcuts depending on the browser you're using: