This might not be the answer you're looking for but the way I see it, it's just another day, and we generally put far too much pressure on it and on ourselves on it, and that it's perfectly fine to not do anything special.
If for your own reasons you really do want to celebrate anyway, try and make/order your favourite meal, think of a good movie or two that always make you feel nice, and spend your evening enjoying those, but most importantly - don't feel down or bad for being alone, there's nothing wrong with that, and even if it feels like there is, this one night has very little significance in the grand scheme of things.