Board Thread:General Discussion/@comment-10197675-20130806142227/@comment-6881629-20130806201734

The Dwemer wanted to use the Heart of Lorkhan (the heart of the god that made the planet) to become gods themselves the Chimer (Dunmer) who were always on rough terms with the Dwemer  though this was a insult to their gods (the Daedra) and started a war. During the  massive Battle of Red Mountain the Dwemer tried using the Heart and all (but one) instantly vanished. The general theory is it back fired somehow backfired removing the Dwemer from reality or even all existance, the wiki page for the Dwemer is here.