Why is the side bar on my quickbooks empty ? on my other business I have links to Invoices, customers, reports etc ?

Welcome to the Community space, Cathy. Let me provide steps to see your desired details on your Menu in QuickBooks Online (QBO).

You can have the option to customize your Menu settings for easy access in managing your business. To proceed, you can follow the steps below:

1. Login to your QBO account.
2. From the Menu page on the left panel of your screen, click on the pencil icon ✎ beside the Menu dropdown.
3. Tick the box to show on your Menu. You can also choose the order of your Menu sections.
4. If you want to create shortcuts to your most used pages like Invoices, Customers, Reports, and more, you can click Bookmarks and search for your desired page. Then put a checkmark on the box.
5. Click Save.

Please refer to this article for more information: Understand the navigation menu in QuickBooks Online.

If this isn't the case on your end, let's try accessing your account using a private window as it ignores data history. It could be that the stored data on your browser is the reason for the missing sidebar in your QBO. 

These are the keyboard shortcuts:

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

If you can see the sidebar after using incognito, then it's safe to say that it's being caused by your browser. Let's clear your regular browser's cache to refresh.

Furthermore, this article may be helpful if you want to switch between different views of accounting in QBO: Switch between Business and Accountant view in QuickBooks Online.

Keep in touch if you need further assistance with your Menu settings or any QuickBooks-related queries. I'm here to lend a hand. Take care.