Forgot my six digit passcode

So, i changed my passcode to a six digit number. i don't remember my passcode but I do remember the last number which is a 6. Also, I can't use Imessage because in order for me to usee it, I have to unlock my phone with the six digit password but I can't remember it. I don't know what to do. I was told to call Apple but I was told to do it online so that someone can help me out

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