SCREENSHOTS OF LOCKDOWN VIRUSES:
Once your computer get infected by one of these viruses, just turn your computer OFF then turn back it ON. But before loading the windows, just press F8 to get Windows Boot Option Menu. Choose Safe Mode with Networking (as shown in the figure below), connect to the internet and open your browser, then download Malwarebytes (free or by purchase). Once it is downloaded, install it to your computer (follow the instructions of malwarebytes installation wizard). Scan your hard drive.
Sometimes these viruses become active while you are connected to the internet even you are in safe mode with networking. Other option is to get malwarebytes scanner on your usb device or on cd/dvd.
You can try also System Restore.
System Restore helps you restore your computer's system files to an earlier point in time. It's a way to undo system changes to your computer without affecting your personal files, such as e‑mail, documents, or photos.
Open System Restore by clicking the Start button . In the search box, type System Restore, and then, in the list of results, click System Restore. If you're prompted for an administrator password or confirmation, type the password or provide confirmation.
Follow the steps in the wizard to choose a restore point and restore your computer.
Note: After you've done a System Restore, it is highly recommended to scan your hard drive by anti-malware or anti-spyware.