1. Take action immediately. Any delay can increase the time that thieves have to freely move through and use your information, making it imperative to act as soon as you feel or see that there is something wrong. The sooner you begin working through the theft, the sooner things will go back to normal.
2. Carefully look through your information. If a service has sent an email with specific points of concern, begin with those. Log in, check the status of your accounts, and make a personal note of anything that seems out of the ordinary to you. After you've done this, move on to other accounts, especially ones that are associated with these bank accounts or credit cards.
3. Don't be afraid to take charge and contact necessary parties. This means banks, credit card companies, stores, even home and apartment complexes or public institutions - don't be afraid to get in touch with them as soon as you feel that there is a need. Even if this type of contact turns out to be unnecessary, it's better to be safe than sorry, and it will be a simple matter of a second phone call, visit or email to let them know that it was a false concern, that things are in fact ok.
4. Make necessary changes. If there is an actual case of identity theft, the recovery process will take some time. The best thing that you can do while waiting for things to return to normal is to let the thieves know that you're aware of what's going on - and put an end to their access. Closing accounts, changing passwords, cancelling orders - all of these will impede the actions of the thieves, letting them know that their reign of terror within your accounts has come to an end. Although you may not get everything back all at once, you can effectively stop further problems from arising via the same thief and account access.