How old is the battery? Any white/green corrosion around the connections?
Like Bert and Mizzou said, I would remove the cables from the terminals and scrub both of them with a wire brush. Getting a more clean connection. I would also have the battery tested to see if it has any juice left. If the battery is dead then you found your problem. My guess is that doing those two things will solve your issue.
If not then the next steps I'd take is checking the starter and alternator. I agree with the others that it's likely a power issue than a fuel issue.