What to do if you already gave information to a tech support person
If you think that you might have downloaded malware from a phone tech support scam website or allowed a cybercriminal to access your computer, take these steps:
Change your computer's password, change the password on your main email account, and change the password for any financial accounts, especially your bank and credit card.
Scan your computer with the Microsoft Safety Scanner to find out if you have malware installed on your computer.
Install Microsoft Security Essentials. (Microsoft Security Essentials is a free program. If someone calls you to install this product and then charge you for it, this is also a scam.)
Note: In Windows 8, Windows Defender replaces Microsoft Security Essentials. Windows Defender runs in the background and notifies you when you need to take specific action. However, you can use it anytime to scan for malware if your computer isn’t working properly or you clicked a suspicious link online or in an email message.
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If you don't feel like doing this right away. Turn off the computer until you do.