Regarding the 750, kick starting a bike has nothing to do with the starter. If it won't turn over with the starter or with the kick starter, then the engine is possibly seized. Now, it could be a situation where something in the starter loop is bad (solenoid, battery, starter motor, ignition coils). And at the same time, something is wrong with the kick starter (reductor gear, starter clutch or starter spring).
Either way, you're going to have to crack open the engine casing to fix the problem. If you don't have the experience to do it, it can still be done. There are a gazillion YouTube videos that will explain the process. But before you jump on something like that, I would highly recommend having a close friend or family member nearby who knows what they're doing. Because you are inevitably going to find some things in that engine when you crack it open that are going to cause you to need to ask questions of someone.
Of course, this forum is pretty awesome at handling those kinds of questions as well.