Usually this requires you to answer a security question, have an email sent to a pre-determined alternative email address, or log in from a pre-determined safe computer.
The information that we provide is deliberately limited for privacy reasons, and we while we won’t tell you exactly which breach you were compromised in, you can cross reference the date (from the Breach Alarm alert) with our Sources Page, which should narrow down the possible websites.
Firstly, double and triple check the email and password that you are entering.
If you still can’t access it, you need to reset your password by following the instructions set out by your email provider.
If you do this, and your password has been compromised, then all of your online accounts are potentially compromised.