It's an era of holding shares in the electronic or demat form in India. However, it is highly possible that you would have suddenly discovered old certificates during spring cleaning or have inherited shares and the holder never bothered to convert them to electronic.
Check if the company still exists
Over the years companies go through takeovers, amalgamations or simply shut shop. The first thing you need to do is check if the company has not closed. In case it is liquidated there is very little recourse that you may have.
a) In case of amalgamation
In case of amalgamation you will have a lot of tedious work to comply with. You will have to see how many shares were allotted of the new company. For example, if you held physical share certificates of Ranbaxy then you should see how many shares of Sun Pharma you would get. This is just an example and you may have to do some research on your holdings.
b) Open a demat account
You would have to than open a demat account and convert the physical certificates into electronic form and receive shares in the new company.
Now, to do this you must remember that in case you inherited shares than there is a long procedure that would apply to get the shares transferred. If there is no WILL or second holder the procedure is even more complicated.
c) In case you have not received dividends
In case you have not received dividends from these companies in the last few years, you can claim for dividends provided the company has not been liquidated. In such cases you may get the dividend for the last few years, as the unclaimed dividend (after a few years) has to be surrendered by the company to the government and would go down as unclaimed dividend.
Look for change in the name of a company or else you might think that the company is liquidated.