most likely exactly the case that i had. Do yourself a favour and check your 'run' switch. Take it off the handlebar, check it for continuity when 'on' and give it a good clean. Bobs most likely to be your uncle and Fanny, your aunt.
my first guess would be the altenator.
its quite simple just remove your seat and fairing and almost directly below where the seat is your battery is sitting upright. just disconnect the cables and pull it out.how do you remove the seat on a vfr 400