Aug 17, 2018 - 12:53 PM
Within 24 hours, you should always send a thank you email to the person who interviewed you. If you believe you failed, then you can also use this email to request a second interview. You will need to explain what went wrong, such as if your poor performance was due to illness. You also need to emphasize how much you want the job and mention how the interviewer can speak with your references.
There are no guarantees an email will work, but it is certainly worth a try. If you cannot secure a second interview, then you should at least learn from your mistakes. There is no need to beat yourself up over the incident. No one can be perfect all the time. You simply need to do better next time.