The button for New, Reply, Reply to All and Forward buttons are all greyed out. Any reason why that would happen all of a sudden?
This could happen for two main reasons;
- You have no email account configured (anymore).
To configure an account choose Tools-> Email Accounts or Tools-> Account Settings
(the exact naming depends on your version of Outlook)
- Your version of Outlook hasn’t been activated yet or your trial has expired.
To activate your version of Outlook choose Help-> Activate Product…
If your trial version has expired you’ll need to buy an Outlook license if you want to continue using Outlook.