Can one start same business again which he sold to someone else

At the age of 61 my uncle he was diagnosed with a spin problem for which he had to undergo a complex operation. At that juncture of his health he was mentally depressed and thought he will never be able to recover even after operation and hence have sold his shop (name and stock as shop was not owned by him) to an amateur in Dec’15. And he went on to undergo the operation and by god’s grace within 5 months i.e. by April’16 he has recovered. He didn’t get into any agreement while selling that he will not restart the same business, so wish to understand if he can restart same biz in the same mar