Will Allah be angry with one who fasted Ramadan without prayer or purification, and practiced masturbation and watched obscene images during his fasting for many years, then repented and became diligent in his fasting? And will this prevent the acceptance of his repentance? And how can he expiate his past sins?

You must abandon sins and be diligent in prayer, as neglecting prayer is one of the greatest major sins. If you abstain from forbidden acts and are diligent in acts of worship, Allah will accept your repentance and forgive your sins, and one who repents from a sin is like one who has no sin. The fast is valid for one who committed acts that break the fast, being ignorant that they were among the things that invalidate it. As for the prayers that were missed in the past, it is more prudent to make them up to avoid dispute.