Neutral sensors rarely go bad. It is usually an actual bar on the shift drum that makes the contact. You may however, want to check the connection on your engine case. Also, your ignition system and starting system is wired so that your kickstand switch must be open (kickstand up) while the bike is in gear. If the connection on your neutral switch is bad, then your bike obviously will not start with the kickstand down. Bottom line, CHECK YOUR CONNECTIONS on your neutral switch, and kickstand switch, and clutch switch. I can almost gaurantee you have a bad connection somewhere. All three of those switches is integrated in your starting/ignition systems. Easiest way to do it is get a multi-meter and do resistance checks and voltage drop tests on the switches.