To resolve the issue of missing or disappeared emails in your Outlook outbox after attempting to send them, here are some things to try:

1. Run an Anti-virus scan on your computer
2. Check to make sure your computer is connected to the internet
3. Ensure Outlook is the primary email client on your computer
4. Check your Outlook account settings
5. Make sure the Outlook outbox is not full and no messages are stuck
6. Delete any messages 'awaiting to be sent from the Outbox
7. Reboot your computer and re-open Outlook
8. Make sure your emails are not being blocked by your network