Browse the account from MP's built in browser. If you are logged out from your account in MP's browser and are unable to login with the correct details your account is most likely banned. If it's an authority account you can try to get it back by claiming that you have been hacked here:
https://help.instagram.com/contact/740949042640030
If it's a smaller spam account there is probably no point in trying to restore it, you better get a new one.
Instagram's "help I got hacked" form works in the way that they are scanning your email reply for keywords such as the original email that was used when creating the account. For example when you receive this email from Instagram, all you have to do is reply them with the original email connected to the account because that is what the bots are detecting and THEN the email is forwarded to a real person.
https://gyazo.com/950e37d41f69f3c1ef81b197eb2e8b1f