Is it obligatory for someone who forgot what they read from the Qur’an or the adhkar to repeat the reading from the beginning?

There is no need to re-recite the Qur’an or adhkar from the beginning due to doubt or forgetfulness. It is sufficient to recite from where you think you reached, or from where it is easy for you, because their order is not obligatory, and their origin is not a duty. The matter in this regard is flexible, and repetition reinforces whisperings (waswas). One of the most important ways to dispel waswas is to disregard it.