Welcome to the Community! I'm very sorry you experienced this. We would love to be able to troubleshoot but will need some additional information.
1) What did you name the campaign that is now missing?
2) Around what time did you notice it was missing?
3) What time did you send the test email?
4) And just to be safe did you look in your spam/junk folder?
This will help us investigate and figure out what is going on.