I am taking action and changing account information on those that have been compromised immediately.
I highly recommend using the insights they provided to find if your data was leaked and from where so you can also take corrective measures right away. To find out if your email address and/or password were hacked, go to: https://haveibeenpwned.com/. This page lets you check your email address first. Next, you can select the tab "Passwords" to find out if your passwords were compromised.
If you find that your data was leaked, you can scroll down a bit and discover from where it was leaked and what level of information was included in the leak. It could be simply an email address or worse, an email address with a password, or other more serious information like address, family information, and so forth.
To give you an idea of if you might been part of a leak, if you had any of the following types of accounts: Bitly, Disqus, Forbes, LinkedIn, and more. However, the leak referred to in this instance with the 770 million plus accounts exposed is called Collection #1. This leak is an compilation of over 2000 previous leaks.
What action can you take:
- If your passwords were compromised, change them to very strong passwords immediately and don't reuse the compromised passwords for anything.
- If your email address was compromised, find a new one and treat it like you would if you had to change your phone number: Contact those people who need to contact you and give them your new information and omit the others.
- Write your passwords for your accounts in a book that you keep in a safe or safe deposit box. This way you know what they are. Paper in your home safe or in a bank's safe deposit box cannot be hacked. (If someone did break in to either to steal information, you would also know right away unlike with hacked data.) Doing this is also important should anything happen and you were to die so that your family can get all your accounts squared away that need to be.
I cannot recommend the password managers recommended on this site as I do not have enough information about them. Furthermore, Any online that can store your password can ultimately be hacked - and those that are known to store crucial information of that sort are the ones most likely to be targeted by hackers.