Forge Minecraft Won't Load

I have been trying to get pokecentral pixelmon, or the pixelmon mod to load, i have it loaded it once, and when i logged out, it won't load again, the mod i used was taken from here, https://reforged.gg/. It has been stuck on the preparing screen for around an hour now. Also, whenever i close minecraft, it won't open again unless i restart my computer, can someone help me fix this problem.