My 2005 Honda Rebel 250 won't start, can anyone help?

I drove a couple hours to look at the bike, brought a trailer to tow it since I just got my license and wasn't comfortable driving it all that way yet. It was driving fine, no problems, no leaks. We tied it down on the trailer and I towed it for about a 2 hour drive. When I got it home there was a small puddle of fuel under the engine coming from one of the black hoses that sticks out underneath. Now it won't start. Before someone asks, YES I had gas in the tank, the clutch in, kickstand up, killswitch to "on", fuel switch on, key in, turned to "on" and the engine in neutral. What would cause this and how can I fix it to get it running again? I was also told it might be an adjustment to the altitude since I went up more than 4,300 ft. Could this be true?

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