There are 3 basic things an engine needs to run. Air, fuel and spark. The way to solve non-starting problems is to be methodical. First identify if your problem is air, fuel or spark related starting with the easiest things to check first. Is there fuel in the tank? Is there anything preventing air from getting into throttle bodies (rodents love making nests in airboxes and intakes)? Is there spark? While it is possible that old fuel somehow is preventing the fuel injectors from working it is unlikely. A simple test for spark is to pull a spark plug cap, put a plug in it, place the ground of the plug against the head and crank the engine. If you see spark, you've got spark. If not, you need to figure out why you don't have spark. The simplest reasons for not having spark are things like the kill switch is on, or the side stand interlock is bad, etc. If you've got spark and the air intake and airbox are open, then you're going to need to go through the fuel system.
Given your description of how you got to where you are, my money is on an interlock problem. Good luck finding your problem.