Does anyone know why or how the rest of the Critias:?

Question

Does anyone know why or how the rest of the Critias
(BY Plato is missing? Or where it is? Any sources wanted!

Answer 1

One view has it that it was accidently split from the Timaeus into two different dialogues (first citation). This is supported, I suppose, by the fact that Timaeus and Critias show up in both dialogues.
Another view has it that the Timaeus and Critias are one of several dialogue pairs. (second citation)
It could also be a triptych, missing its third component, something maybe corresponding to Euthyphro/Crito/Apology
The omission might be intentional: the aporetic state (state of puzzlement or confusion) shows up all over in Plato. For example, Euthyphro ends with Euthyphro, having absolutely no answer for Socrates, running away amid Socrates protests. Now Critias is probably from alot later in Plato's life. And as a mature philosopher, he very likely is revisit themes from earlier in his career. An audience is even more likely to think things through when they are dropped into confusion to try and think things out
The Timaeus has lots of unexplainables too, (like invocations to the Muses during speeches about science)
Finally it is also possible, that while writing the Critias, Plato changed his mind about the project he was attempting. Maybe the Timaeus is really the (revised) Critias. But supporting this conclusion would involve comparing the two in much more detail.
Hope this helps