If you bought the phone aftermarket or from a person, you may have no choice but to purchase a phone in your area, or from the right area. While many phones allow for installing language support, that doesn't mean it will add that option to all things on the phone.
Now you can add it to the keyboard.. Go into "Settings" and then "Language & Input". Now tap the "Settings" icon (gear) next to the main "Google Keyboard". You will be presented with a long list of language options to add to the phones keyboard.
In regard to adding languages for the entire phone, without rooting the device I know of no way to add them to that older android version. Actually even newer versions run into this problem as companies tend to make a phone only have languages common to the area where they are being originally sold. Since your phone was probably not meant to be used in India, there is where your problem lies.
To get help with rooting, please post in the "Rooting, Jailbreaking & Unlocking" Forum.
http
/www.tomsguide.com/forum/forum-117.html