What is the solution to the problem of frequent doubt concerning the performance of all the pillars and obligatory acts of prayer, and is the prayer acceptable despite these doubts?

If a worshiper experiences excessive doubt, imagining that they have omitted something from their prayer, they should disregard it, and their prayer is valid. They should consistently recite adhkar, especially the morning and evening remembrances. If a Muslim performs an act of worship correctly and with sincere intention for Allah, then Allah will not let their reward be lost.