OK so we all have seen there bloody ruins but who are they the cant have all just suddenly diapered i mean how is that possible can anyone help me here who are they and were did they go i need to know

the Dwemer, or "Deep Elves" were another race of mer..

I remember hearing someone on these forums say they became the skin of the Numidium or something along those lines.. but yeah, they are long gone and won't be coming back..

although, we did meet one in Morrowind (Yagrum Bagarn) who escaped the catastrophe that befell the rest of his race. its been awhile since i played Morrowind, but i think he was in a realm of oblivion or something when the rest of his race went poof.. granted, considering he had Corpus, he may still be around today. who knows, we haven't heard anything from him since morrowind

The dwemer were, succinctly, atheists in a realm where gods are very real. They meddled with the fabric of reality and accidentally blinked nearly their entire race out of existence. Maybe. It's all very unclear what happened, as their knowledge and command of the arcane were probably beyond even the Psijic Order's. It's possible that they became the skin of Numidium, their own giant brass golem "god" that they created to refute existence itself.

Arniel Gane in Skyrim's College of Winterhold gives out a side quest line that may very well have him recreating their disappearance event in microcosm.