1) since your father was co owner of property your uncle had no power to sell the same without your father consent .
2) take search in sub registrar office whether Sale Deed is registered or not . also take search in court records for orders passed for handing over land for recovery of Rs 30,000
3) your father can move court to set aside sale of property sold by your uncle .
4) before moving court issue legal notice to your uncle that it has been brought to your notice that property is being sold without consent of all legal heirs .
5) you may also file criminal complaint of cheating , criminal breach of trust against your uncle .