My PC was jacked why?

[Adam]

It started talking to me and took pictures of me via webcam and hacked my twitter. I think I removed it but how do I check?
I think its gone now but I don't want to format the PC
There was a person on the other end contacting me and knew where I lived he posted info about me.

[jegs]

Back up your data, format the drive and reinstall the operating system. Install a good anti virus.

[Frozen Penguin]

Download Malwarebytes and Free AVG, run Full Scans to be sure your computer is free of malware/viruses:
http://free.avg.com/ca-en/homepage
http://downloads.malwarebytes.org/mbam-download.php

[Fred]

Nobody hacked it. Unless you open the firewall on the computer and the router, and then leave some program open to remote access the chances of hacking are minimal. They would still need to guess your user name and password. Millions to one chance against it. Do not confuse fiction with reality. You have carelessly followed a link sent by someone, or opened an email attachment from them and it contained a remote access program. So you let them in. Download the free scanner from http://malwarebytes.org and run the full scan.