If you cannot find the started form in your Enrollment account dashboard, it is most probably because you had accessed the registration form link from your Parent Portal account. When you access the form using your parent portal account the form is started through an SSO account in the Enrollment portal. To be able to access your in-progress form you would need to access it using the Parent portal account again.
If you still cannot find the form, I would suggest you work with Support through a case and have them assist you to access the form again. You can click this link to reach out to them.