What is the ruling on prayer if I prayed before making sure whether the fluid discharged from me was semen or not, relying on its smell after it dries? And what is the ruling on prayer if I prayed, and then hours later it became clear that it was not semen because there was no smell after it dried?

The scent is not the sole indicator of semen. The ruling on prayer relates to whether ghusl (definition) (ritual bath) is obligatory in this case. Whoever experiences a wet dream and finds moisture but is unsure whether it is semen, must perform ghusl according to some scholars, and must repeat the prayers performed before that. The questioner must repeat the prayers she performed in a state of impurity. Ibn Taymiyyah holds the view that whoever does such a thing out of ignorance is not obligated to repeat past prayers, but only to repeat the prayer of the current time and adhere to it in the future.