What are the documentary evidences available with you other than witnesses?
Though the business documents are on his name and the company's registration also done on his name, and it may be a proprietorship company too, do you have any evidence for funding or investing your money into the business?
Have you been working with him in the said business,do you have evidence for that, if so whether any salary r other withdrawals were made by you which reflected in the books of accounts ?
Whether your capital found place in the annual audit report?
You may collect all these evidences and with the help of an advocate as well as an auditor, create substantial evidence and file a suit for recovery of your profits in the business as well as to withdraw your capital from the firm due to cheating, fraud and other undesirable activities of your brother in the company.