What is the ruling on my ablution and prayer after I doubted whether I had removed petroleum jelly from my feet, and does that affect the validity of ablution and prayer?

The questioner is afflicted with waswasah (whispers/obsessive thoughts), and she must disregard these whispers and not pay attention to them. Washing petroleum jelly with water and soap is sufficient to remove it, and feeling the softness of the foot does not mean it remains. As long as there is a strong presumption that it has been removed, doubt should not be entertained. Similarly, doubt about water reaching the cracks in the foot should not be entertained because it arose after completing the act of worship, and doubt after completing an act of worship has no effect. The questioner's prayer is valid, and she is not required to repeat it.