What are the consequences of abandoning prayer and masturbating for years, and is it necessary to make up missed prayers after repentance?

No matter how great the sin, Allah's forgiveness is greater, and sincere repentance removes it. Its conditions are: abstaining from the sin, resolving not to return to it, and regretting having committed it. If the sin involves the right of another human being, then restoring that right to them must be added. Abandoning prayer is a sin, and it is more prudent to make up for the missed prayers, as this resolves the differing opinions.