Is Notarized document a valid proof for financial claim?

I had got into an contract with one director of a company and invested some amount of money. That contract was Notarized too. Investment was made through cash and bearer cheque in the name of another company. Cheque numbers are mentioned in the contract. He was supposed to monthly pay back the investment with a return starting from three months after the investment. But that man has not paid back a single rupees yet. Its been one year now. Is notorised document a valid proof for my claim?