Pretty much all small engines today are built to easily handle up to 10% ethanol in gas - though not the high-ethanol blends. Couple of steps to go through before taking it to a repair shop - listed in category Lawnmower and Small Engine Repair, as I recall. Following steps assume a manual start generator - if electric start then when talking pulling rope use electric starter - if won't crank, then probably discharged or dead battery.
Check your troubleshooting guide for your engine. If you do not have and can't find one on the web, try these steps in order till you find the problem or it runs:
1) make sure it has gas in the tank, that it is not all dirty or sludgy or varnishy, and that you do not see a water layer on the bottom if you gently tilt it back and forth. IF it has a fuel filter with glass bowl, check that does not have water in the bottom either - drain if it does.
2) make sure spark plug wire is securely gripping the plug - if loose, normally up inside the "cup" end you will see a curved sheet metal circle that goes around the tip of the spark plug - GENTLY, without crushing it, tighten it down a little bit with some pliers.
3) prime it - usually a rubber red push button, press several times AFTER you feel fluid pressure under the bulb - may take a couple of times just to start priming.
4) turn on start switch if it has one
5) put choke on START or FULL
6) pull full extent of rope five times, or until it fires and starts first time but then chokes out
7) then put on half choke position and pull several times till starts, moving choke to OFF or RUN position once it has run a bit and then starts to run rough or smoky, which means it is getting too much gas. Some have an automatic choke so no choke switch.
8) if that does not start it, remove the plug wire from the plug and peel the rubber covering back from the sheet metal loop so it is exposed, and with INSULATED pliers (so you don't get jolted by the high voltage) hold it about 1/8" away from the spark plug end while someone else pulls the starting cord - you should see a spark. DO NOT do this yourself if you have any type of electrical implant or medical device on you. If no spark, then try same thing holding the wire near an exposed bolt head on the engine - and see if there is a spark. If no spark in either case, probably an electrical issue that is probably beyond your repair capability unless you have some mechanic experience. If sparks at bolt but not spark plug, replace plug. If sparks at both, remove plug and check for black greasy oiling or buildup of combustion products or lack of a gap between plug tip and center prong - if so, replace plug with IDENTICAL numbered plug - no added letters after the number which the existing one doesnot have like J or Y for instance - those tail numbers mean specific uses or extended center reach, which can damage your engine fi used and not on original one. Do NOT overtighten - snug tightening similar to what it took to loosen it, do NOT reef on it or you can strip the threads. If not dirty, smell for gas on the plug tip - if gas smell replace plug. If no gas smell, then lack of fuel is likely problem.
9) If lack of fuel is suspected and you are a bit mechanically inclined, try disconnecting fuel hose where it goes into carburetor after coming from fuel tank - if gas flows out, likely OK. If no gas, maybe fuel filter canister is plugged - try disconnecting hose to see if fuel flows out of there.
10) Try again priming a half dozen times, and pull on rope on START or FULL choke a half dozen times or till it starts to run and coughs to a stop, or until you smell raw gas smell. If you do smell gas at the exhaust or gas starts running out the exhaust, wait a couple of minutes for it to evaporate, then try starting on RUN or OFF choke setting, because you are getting gas to the cylinder and plug
11) If no joy with any of the above, then small engine repair place, or a friend who is gas engine savvy are your next step.