Please help me with this.

If you suspect that an account has been breached, then the first thing that you should do is change your password for that account.

But do this by visiting the website directly, rather than by responding to, or following any links given within e-mails.

Just in case the e-mail informing you of the breach is a fake scam e-mail attempting to trick you into entering your passwords or other information into a fake site.

If you need to do other things as well as changing the password, then hopefully someone else will post here and inform you of them.