Would do a spark check, preferably with an inline neon tester from the parts store since you have a heavy smell of fuel. See if you are getting spark and if not, go back and check all the wires and make sure you didn't knock something loose.
Should be no reasons that changing oil would cause it not to start other than knocking a wire loose somewhere, possible a coil wire, something small that may not be so noticable at first. Also look for any circuit breaker or fuses that may be hidden that could kill the ignition circuit.
Best to backtrack to the steps you did when change the oil and start in those area of where you all may have knocked something loose.
Good luck and let us know how you make out