What is the way to sincere repentance and a return to commitment after falling into hypocrisy, while feeling a dead heart and a constricted chest, and fearing that repentance will not be accepted?

Fear of hypocrisy is a good thing, but it must be accompanied by hope and good presumption of Allah. Approach Allah with sincerity and truthfulness, reflect upon death and its horrors, and upon the names and attributes of Allah, and be mindful of His awareness of you. Have a good presumption of your Lord and do not despair of His mercy. Supplicate Him to mend your heart, for hearts are between two of His fingers, He turns them as He wills. Keep company with the righteous, increase in remembrance of Allah, seek sacred knowledge, and recall your sins in a way that motivates you to sincere repentance and a firm resolve to be steadfast. For whoever strives for the sake of Allah, Allah will assist and guide him, in accordance with His, the Almighty's, saying: "And those who strive for Us – We will surely guide them to Our ways. And indeed, Allah is with the doers of good."