I ran into an interesting issue today. Windows Server 2012 R2 had no options to mount an ISO file. I tried a couple of 3rd party programs to do it but they would not work either. I found a command that can be used with PowerShell to mount an ISO and it worked perfectly. Here's the text of the command.
Good luck!
Mount-DiskImage -ImagePath 'D:\Path\To\Image.iso' -StorageType ISO -PassThru | Get-Volume
