How can I get the iron rods to lower in the last room? It's in High Gate Ruins.

Mate, the dungeon is different for everyone so you have to give us its name.

Are you in Mzinchaleft? If so, http://www.uesp.net/wiki/Skyrim_talk:Mzinchaleft#Room_with_levers

If not:

There's 3 levers. The third lever that presents itself after you have fought the released draugr will trigger the gate.

If Highgate has already been cleared and Anska has her scroll, then You are going to need to cheat by using Console commands. You should make a save before doing the COW book any Guilds random fetching quests. The Radient AI has some flaws in the choices of Dungeons for fetch quests. You may be able to jump up the first room and use the exit from the final chamber to get back in?

Thanks

Cool, I hope you sorted the real problem (since it wasn't the levers, after all)?