We have multiple tools to help you automatically diagnose an issue, troubleshoot, and fix problems with Outlook.
Microsoft Support and Recovery Assistant
The Microsoft Support and Recovery Assistant can help you automatically diagnose and fix a range of Outlook problems. You will need to download the application to your local computer, sign in with your home, work, or school account and select the issue you want help with.
The Microsoft Support and Recovery Assistant will run a series of diagnostic tests on your computer and help you set up a new profile, or resolve other issues. If any of the tests fails, it will provide suggested solutions to get your problem solved. If you're having a specific problem in Outlook, you can also try one of the following Microsoft Support and Recovery Assistant links:
Outlook won't start? Download the Microsoft Support and Recovery Assistant to help fix the startup problems.
Can't send or receive email from Outlook? Download the Microsoft Support and Recovery Assistant to let us fix the problem for you.
Having trouble connecting to your email from Outlook on your desktop? Download the Microsoft Support and Recovery Assistant to diagnose and fix errors in your Outlook mail profile that might be causing the issue.
For more information and to install the tool, see: Automatically diagnose and fix Outlook issues.
Office 365 Support Corner: These videos are created by Office 365 support engineers to help you learn more about Office 365, and are focused on support trends and top how-to questions and issues.
Calendar Checking Tool for Outlook (CalCheck)
CalCheck is a program that checks your Outlook calendar for problems, and performs various checks on general settings, such as permissions, free/busy publishing, delegate configuration, and automatic booking. Then, each item in your calendar folder is checked for known problems that can cause unexpected behavior, such as meetings that seem to be missing.
For more information and to install the tool, please visit: Calendar Checking Tool for Outlook (CalCheck).