First, go into your Domain Manager to be sure the email address on the domain is valid. Sometimes a small misspelling goes unnoticed, so the email is not received. If you need to update that email address, you can use these instructions.
If that's all good, be sure to list @godaddy.com as a preferred email sender before sending the approval email again. You may also wish to temporarily disable your email filters and resend. Then approve through the instructions on the email sent.
TLH - GoDaddy | Community Moderator Supporting you at x.co/247support