I don't know the story of your EBS environment. What patch you applied? How did you enabled Telgu- NLS Support, how did you uploaded telgu translation data to your EBS? When and How was the issue started? Do you have this problem for all your OAF pages (including the standard ones) or only for the custom one? so on and so fort.
If the Telgu data is correctly loaded in the database and if you just can not display it on your OAF screens, then start by checking the profiles.. Here ->
http://ermanarslan.blogspot.com/2015/03/ebs-r12-oaf-nls-character-problem.html