Open the Instagram app and click on “get help with signing in”. If your account is linked to a phone number you can enter this to receive a code as a text message. Just enter this code and your account will be recovered. If you don’t have a phone number linked you need to click on “need more help” followed by “I can’t access this e-mail or phone number”. This will open up a support ticket which you can submit. Fill it in as thoroughly as possible. The support team at Instagram will get back to you with instructions on how to recover your account.