It is obligatory to recite in the first and second Rak'at of every Prayer, Sura Al-Hamd and another Sura. Reciting must be by your tongue and not in your mind only. If you have difficulty in reciting, you should recite in the way which you can, even if it is not perfectly correct, as far as it is the best that you can. Remembering the Sura in your mind is not reciting. Those who totally paralysed should remember the Sura in their mind because that are totally unable to move their tongue nor their lips, but as you are able to move your tongue and lips, you must recite the Sura in the way which you can.