The knowledge 'I am', to which you have to come back, is the very first one that appeared on you and you came to know that 'you are'. At that moment you knew nothing about words or language, that sense of being was non-verbal. You will have to apply yourself to grasp that state again, you have lived that state, it was the period from when the 'I am' arose till you were taught to communicate verbally using words. Come back to that state and do not deviate from there for even a moment, you have to relive that state, only then will you understand it and then it will disappear!