You can remove viruses from a Windows PC using tools such as Microsoft Safety Scanner and the Bitdefender Rescue CD. If you know the names of the viruses, you can search an antivirus vendor's website for instructions on how to manually remove them.
To scan the computer using the Microsoft Safety Scanner, visit the official Microsoft website, download the tool, run it with administrator rights, and follow the instructions in the wizard. If you can't download the tool due to the viruses interfering with your Internet connection, restart the computer, enter Safe Mode with Networking, log on with an account that has administrator privileges, and retry accessing the Internet.
To scan using the Bitdefender Rescue CD, first download the Bitdefender Rescue CD image from Bitdefender.com; then, use it to create a bootable device, and boot from the device. Once the Bitdefender Rescue CD wizard opens, select the language you prefer, press Enter, and then click Continue to agree with the terms in the License Agreement. The Bitdefender scanner should automatically update and start scanning all drives on the computer. Once the scan is complete, remove or quarantine any viruses found. Next, exit the Bitdefender Rescue CD, eject the bootable device, and restart the computer in the normal mode.