Landlord Denies For Sale Dead

Bought 10 3/4 cents of land in Jan 2019 Amount# 425000 {40000 per cent} from my uncle (mother's brother) We have it documented in 50rs bond agreement paper mentioning 350000 lac paid as initial amount (single payment by cash) since landlord was in critical situation and were indeed of money. Document says land needs to be registered within 3months by paying remaining amt, if time lapsed it can be extended by all means and it is sole responsibility of landlord or buyer can reach court by paying pending amt and get the land with the help of law. Signed by landlord and his son with acknowledged by withness Today after covid 19 situation, landlord denies for registration reasoning no more interested in selling land. Question# Does the document only valid if it was attested/registered agreement document in land registration office or even 50rs bond agreement is valid to take legal action on landlord . ( specific to Tamilnadu land registration norms) Location# Tirupathur 635601 TN