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I have a Mojang account and I own Minecraft on it but cannot login to Minecraft using the Minecraft website, the Mojang website or the Minecraft launcher. On the Mojang website I get the error "unknown email or password" and on the Minecraft website I get "Oops, unknown username or password. If you are logging in with a Mojang account make sure to use your e-mail address as username." I also can't login to tekkit using it either.