Recover from a system hack

Clean your computer

Install antivirus software.
Symantec Norton Antivirus Plus, McAfee Antivirus, Webroot SecureAnywhere AntiVirus, Bitdefender Antivirus Plus, and Kaspersky Anti-Virus are some of the most well-known products, as noted by software-industry publications such as ComputerWorld. Bonus: Most anti-virus software also scans for malware.

Scan for and remove any malware.
Malware—software designed to disrupt, damage, or gain unauthorized access to a computer system—can allow someone to access files on your computer or reroute the website you land on from a legitimate one you enter to a fake one. Check your computer to confirm all traces of this type of program are eradicated.

Check for unfamiliar programs or applications.
See if a hacker installed a lurker programs that could be sending information stored on your system to an unauthorized source.

Update your operating system software.
Use the most current version of this software, which will have the most recent patches and bug protections incorporated. Make it a practice to accept automatic updates or at least do a quick version check once a month.

Take steps beyond your system

Review your email account, too. 
Check your Sent Mail folder to assure an email you didn’t send has gone to your contacts list. Also, check your email settings, especially your signature and ‘reply to’ address, and delete any odd links or email accounts you don’t recognize. (For a checklist of what to do if your email is hacked, check out Recover from an email hack.)

Change your passwords from a computer you’re confident hasn’t been compromised.
Make sure your new password combines letters, numbers, and characters.

Put a fraud alert on your credit-report access.
You can request the major credit-reporting bureaus (Equifax, Experian, and TransUnion) alert you when your credit report is requested. You only have to ask one company, which will notify the other two for you.