Does applying hair and face cream prevent water from reaching the body, thereby invalidating wudu and prayer?

It is not possible to determine whether a specific cream prevents water from reaching the skin or not. However, if the substance prevents water from reaching the hair on the head or the skin, then the ablution (wudu') performed with it is not valid. If the ablution is invalid, then the prayer is invalid, and all prayers performed in this state must be redone.