Website Missing from Multisite

There is/was a website setup on our multisite at This website had the domain mapped to it. This site is no longer showing up in my list of sites, yet it shows up against another super admin users account. I can access the site settings from this URL but cannot find the site anywhere else in my system. I am uncertain what to do to recover the site, but we are clear that nobody has deleted this website from the system. We cannot do a full restore from a previous version of the multisite, as we have no idea how long this site has been offline. Help!