A page titled ConnectYourDomain Error | Wix.com means your domain points at Wix, but Wix does not have a live site attached to it.
Three usual causes. The Premium plan ended, so the site went back to a free plan that cannot use your own domain. The site was unpublished or deleted. Or the domain was disconnected from the site inside the Wix dashboard.
If you bought the domain elsewhere (GoDaddy, Namecheap, 123-reg), log in there and check it is still paid up. Then follow Wix's "connect a domain you already own" steps, which set the name servers or records at your registrar.
Want the rest of your site checked after it is back? Run a free 40-point check at tinkeraudit.com.