Click on the search icon, search on ‘CMD’ when you find the application (Command Prompt) run as administrator (i.e. right click it and click run as administrator).
You will then see a rectangular black window appear with folder> then type in sfc/scannow and sit back and wait (takes a while to run). You should see a progress ‘%age’ text. It can take 30-45mins.
When finished type in exit. Then close outlook, restart Outlook and problem solve.
Be careful if you have a lot of emails in the outbox as they will send immediately, so if you have sent them another way , on a phone perhaps, be sure to delete them before you restart outlook.