I accidentally closed the window I was working in and had to open a new one and re-login... I was almost finished with the pic and hadn't sent it in... was everything I'd done lost?

It could've been. Try drawing again, with the same program and same size canvas, and see if a little window comes up to restore it. I do not know if it will do that on lascaux, though.

The window came up but the only thing it restored was what I had before everything I'd done today.