There are a few possible reasons why you might not be able to use audio in Instagram:

• Your Instagram app is not up to date. Make sure to update your Instagram app to the latest version.
• Your device is not compatible with Instagram audio. Some older devices may not be compatible with Instagram audio.
• You are in a region where Instagram audio is not available. Instagram audio is not available in all regions.
• You are trying to use copyrighted audio. Instagram has a library of licensed music that you can use in your videos, but you cannot use copyrighted music from other sources.
• You have a problem with your internet connection. Make sure that you have a strong and stable internet connection.

If you have checked all of the above and you are still unable to use audio in Instagram, you can try the following:

• Restart your device.
• Log out of Instagram and log back in.
• Clear the Instagram app cache.
• Reinstall the Instagram app.

If you are still having problems, you can contact Instagram support for assistance.