LookupAccountNameW

function LookupAccountNameW(

  lpSystemName: LPCWSTR;

  lpAccountName: LPCWSTR;

  Sid: PSid;

  var cbSid: DWORD;

  ReferencedDomainName: LPWSTR;

  var cchReferencedDomainName: DWORD;

  var peUse: SID_NAME_USE

):BOOL;