REGARDING LOAN RECOVERY OF 2 LAKH GIVEN TO A FRIEND

My dad given 2 lakh rupees to one of his friend without paper work only by cash physically reaching.during that time another one friend was present as witness.the borrower persons assured that he would give one lakh as a interest with total 3 lakh in a month.but it is five month almost he does not return the money and phone is switched off when we reached to his home , the door was locked , my dad and he works in a same govt office. So how to recovery the amount. Even he is neither attending office nor picking up phone call.