First of all: double check somehow that i really am the last person, i mean, yeah. everyone disapeering except you including animals would be suspect, at least there might be ONE more thing existing out there.
Failing that i would probably hunker down, try to have fun while power lasted, get as many non-parishable foods as possible (yay for canned spam and condensed milk!) Try not to be too paranoid about aliens, sickness, or whatever the hell happened, then after about 6 months when i've read, video gamed, fast carred, waterparked, and whatever the hell else i do into boredom/sadness probably a bullet to the brain (with an OD for good measure...)