If you feel that you have lost a vmfs partition (now showing as unformatted). I'd open and SR with VMware before you proceed with doing anything else on your own.
In fact, to explain all, one of my colleague set the span box. As there were only one spare VMFS. It was taken without prompt. I reformat the main VMFS. That seems to have liberate the extent. I'm trying to repair the extent. But there is no tool able to do that.
What were you able to find out from support? I have the same problem and am wondering what to do. I am thinking I will call for support before doing anything else.
In fact I give up this problem thinking there is no solution. My company took a vmware gold support and I opened another "easier" case. It is still opened.