A reference entity was broken means its referenced drawing or entity was not found. Update the broken reference entity's referenced drawing path with the target drawing path to fix the broken issue in host drawing.
public static bool RepairBrokenDRef( ObjectId brokenDRefId, string targetDwgFullPath )
Public Shared Function RepairBrokenDRef ( brokenDRefId As ObjectId, targetDwgFullPath As String ) As Boolean
public: static bool RepairBrokenDRef( ObjectId brokenDRefId, String^ targetDwgFullPath )