Transfer of shares of a deceased shareholder

u need to contact the share transfer agent of the company .The details of the agent will be available on the company website.You need to write a letter or contact the R&T agent and they will provide the prescribe procedure for the same.The agent will provide you he list of documents required for transfering the said shares.

But the share certificates are not available. How to get the same ?

only the transfer agent associated with the company can help you in this case.As i have mentioned that you need to write a letter to the company /company share transfer agent clearly mentioning the folio nos of the shares available and mentioning specifically the loss of share certificates.Post that they will verify the name and folio nos  of the holder as per their members register and accordingly reply you with the procedure for applying for fresh share certificates and subsequentlu getting it transferred and converting it to demat form.