Does unintentionally entering a website of magic and sorcery prevent the acceptance of prayer for forty days?

You have done well in your effort to change the evil. Entering a forum or website that is like going to a soothsayer or diviner is an intentional act of entering to learn about matters related to the unseen. However, merely entering it by mistake without intention does not fall under the mentioned threat, due to the generality of Allah's saying: "Our Lord, do not impose blame upon us if we have forgotten or erred," and due to the hadith: "Indeed, Allah has forgiven my Ummah for their mistakes, forgetfulness, and what they are compelled to do."