You could try moving the fermenter to an area where the beer can warm up up to the low 70's and then swirl the wort to rouse what yeast is left. That may restart the yeast and get it to finish the job.
If that doesn't work, I would do one of two things.
1) Brew another beer using 1056 and then rack the stout onto the yeast cake.
2) Sanitize a quart jar and visit your local brewpub or microbrewery. Ask them for some yeast slurry. Pitch that into the stout.
In my experience, it takes a lot of yeast to restart a fermentation.
"You can't drink all day if you don't start in the morning."
Kegged - Where's Waldo Amber Ale
Dry peppering - Jalapeno Wheat
On the fruit - Currant Wheat and Huckleberry Wheat
Primary - FUBAR Weizenbock and Accidental Dunkelweizen
Hops - Centennial, Nugget, Mt. Hood, Cascade, Willamette, Magnum, Chinook