Site offline pointing to a DNS issue

Im helping a customer that has the site DIEZ.COM.CO, site that since monday is offline (WEB and email) and the hosting vendor who is MI.COM.CO informed the customer a DNS issue for this domain, issue located on a Cloudflare server.The account that the customer used to register this domain with Cloudflare is an “[email protected]” account but as the email is also out and dont remember the used password, the account cannot ask a password reset as the email wont arrive to their mailbox as its offline.

How can Cloudflare just confirm or check this domain and validate if indeed there is a DNS problem or not? and how can it be solved if there is a problem.

It’s easier to move the domain to a new account here than it is to jump through the hoops to recover a lost login. Just make sure the new account does not use an email address that depends on access to that account.