Instagram

i have never used instagram and when I tried to see the posts of a friend who said she had posted on instagram, I was not able to sign up because someone had already used my email to sign up with my credentials, but strangely, the email to reply back was another email @hotmail.    No wonder I did not receive any emails from Instagram for anything.  Can the experts advise how I can reclaim my account and see if there has been any untold things done or said under my name, and how do I correct this.  Thank u.