music & geek question

My music wasn't always so thin instrumentally. Two years ago my
leadguitar/bass man had a stroke. (Do look after your blood pressure,
my loves.) It all but rendered his dominant right hand useless, along
with his leg on that side. He tells me he'd rather have lost his legs
than not be able to play guitar. But I think he can play music. He's
taught himself to draw with the left as well as he could with the
right. I think he should be able to play guitar music, lead and bass,
with his left hand. I have a music keyboard but the quality is dubious
if your expectation is rich guitar options. So is there some sort of
computer software that sounds like guitar and base that could be played
one handed? <R>