Does the prayer become invalid if the worshiper says to himself due to obsessive thoughts, "My prayer is wrong, and I must repeat it later," and then discovers that it was correct?

Worrying thoughts (Waswasah) are among the most dangerous ailments, so they must be completely disregarded. What has been mentioned does not invalidate the prayer nor affect its soundness. Therefore, do not repeat the prayer because of worrying thoughts, no matter how much Satan deludes you into believing that your prayer is invalid, unless you attain certain conviction of its invalidity.