I've had a couple "scares" like that, i.e. an entire window full of open tabs disappearing (usually closing it by mistake), but normally they come back with jus

I've had a couple "scares" like that, i.e. an entire window full of open tabs disappearing (usually closing it by mistake), but normally they come back with just a Ctrl+Shift+T. Not saying that's what happened to you, just sharing my experience.