I moved your topic to an appropriate forum category @sksanthosh.
In the future, please take some time to pick the forum category that best suits the subject of your topic. There is an "About the _____ category" topic at the top of each category that explains its purpose.
Railroader is right on. It is very possibly you have already damaged your processor. When using processors you need to be aware of there limitations, this you get from looking at the specifications etc. Had you spent some time reading the forum you would have found this. Also many adds selling them state that. A big hint very few if any processors have internal A/Ds will take a voltage greater then there Vcc. I recommend you remove your 5V connection and re-connect to a 3V3 volt connection and see what happens.