Disable all other plugins. Use the default theme. Try again. If it doesn’t send, try sending to a different (eg gmail) address. If that still doesn’t work, verify that sendmail is installed. If it is, check and see if a basic sendmail php script will work. If that still doesn’t work or sendmail isn’t installed, you may need to contact your host regarding the issue.
If you find it will send to a gmail account, but not to your own @yorudomain account, chances are there’s a DNS or potentially an anti-spam issue that’s blocking the emails. You may also want to see if there’s an outgoing box for sendmail, or error log which shows you what the issue might be.