The most common reason for the Access tab to disappear is that the AOI add-in has been disabled in Excel, often caused by a Windows Update. To check and re-enable it:
Open Microsoft Excel.
Click **File**, then click **Options**.
Select Add-ins.
At the bottom of this screen, next to Manage: change the drop down to Disabled Items and select Go.
Click **Access Office Integration for Microsoft Excel**, then click **Enable**.
Close Excel and then re-open and you should now have the AOI menus available.
If the Access tab is still missing after checking that the add-in is enabled, you may need to re-register for AOI.