It sounds like you may have accidentally activated a certain mode or setting in Excel that is causing the icons on your Insert and Data tabs to be greyed out. Here are a few steps you can try to resolve the issue:

1. Check if you are in "Edit Mode": Sometimes, when you are editing a cell or formula in Excel, the program will automatically switch to "Edit Mode". In this mode, many of the icons on the ribbon (including those on the Insert and Data tabs) are greyed out. To exit Edit Mode, simply press the
   Code:

   Enter

   key on your keyboard.
2. Check if you are in "Compatibility Mode": If you are working with an older version of Excel file (e.g. an .xls file instead of an .xlsx file), Excel may automatically switch to "Compatibility Mode". In this mode, some of the newer features of Excel (including some of the icons on the ribbon) are disabled. To exit Compatibility Mode, click on the "File" tab, then click "Info", and look for the "Compatibility Mode" section. If it says "Compatibility Mode" next to the file name, click "Convert" to convert the file to the newer format.
3. Check if you have any add-ins or macros running: Sometimes, third-party add-ins or macros can interfere with the normal functioning of Excel. Try disabling any add-ins or macros you have installed, and see if that resolves the issue.
4. Try resetting the ribbon: If none of the above steps work, you can try resetting the ribbon to its default settings. To do this, right-click on any of the tabs on the ribbon (e.g. Home, Insert, Data), and select "Customize the Ribbon". In the "Excel Options" window that appears, click on the "Reset" button at the bottom of the screen, and then click "OK". This will reset the ribbon to its default settings, which should restore the icons on the Insert and Data tabs.

I hope these steps help you resolve the issue with your Excel icons being greyed out. If you have any further questions, feel free to ask!