hey dear,
i am using atmel's samd20j18a cortex m0+ micro controller and keil mdk5 compiler but i am not able to find required documents regarding how should i start now project which supporting drivers or files may be included. or ir any ready example available or not.
thanking you.
Go to the manufacturer's website!
Generally, there will be a Product Page on (or from) which you can find such resources...
Simply putting SAMD20 into google will get you there!