Smoke Bake - What to do after crash?

Hello
I am struggling to bake a fire / smoke sim. The bake has been turning over for at least 20 hours and nearly finished but it has crashed. I am looking for a way to continue the bake to the end but as I can’t find anything to explain what all the bake buttons do so I am at a loss as how to move forward.
Any ideas are most welcome.
Thanks