What is the way to restore khushu' (devotion) in prayer and reciting the Quran, and to strengthen faith after feeling distant from Allah and having weak self-supervision?

Abandoning prayer is among the greatest sins. The questioner must offer sincere repentance and return to Allah truthfully. Guidance and uprightness are attained through striving against one's self and fighting Satan. When one is sincere in their striving and patient in obedience, they will taste its sweetness, as Allah Almighty says: "And those who strive for Us – We will surely guide them to Our ways." It is also advisable to associate with the righteous and to frequently supplicate and humble oneself before Allah.