Do. Write. Finish.
I know, you’re saying, “That’s easier said than done.” I know it is! So fucking what? A big-ass boulder tumbles down from the mountaintop and falls on your hand and pins the limb, you either gnaw through your arm like a goddamn coyote or you die under the rock. Door won’t open? Kick it down. Wall blocking your path? Bash it with your skull until it falls or you do.