The most surefire way to know if you’ve been hacked is if you are unable to login into your account. In that case, you should take the following steps immediately:
1. Check to see if you received an e-mail from [email protected]
2. When you find the e-mail, look for the “revert this change” button in the message, and select it. Once you click on it you may be able to undo the change (via Instagram).
You can also request a login link, security code, or support from Instagram to resolve your issue. Instagram may ask you to verify your information with a photo, so they know it’s actually you.
Another sign that the account is comprised is that your e-mail or registered phone number has been changed. This is often the first thing that will be changed so that you’ll stop getting notifications. You can also check the settings page to see if there are unfamiliar devices logging into your account. If you see strange activity such as unknown messages to other people being sent from your account, subscribing to new accounts, or your account is blocked due to spam complaints, odds are strong that a hacker is controlling your account (via RTE and Consumer Reports).
Sometimes, alerts can come from your connections who’ve picked up that something is wrong and will let you know that they think you’ve been hacked.