Can you get to Safe Mode (repeatedly tap F8 after post or bios screen)? If you can get to the Safe Mode options screen, choose Safe Mode with Networking.
Download the attached zipped file. Inside is a reg file that should fix your exe associations and RKill.
Run the reg file then RKill, or vice versa if that doesn't work.
Without stopping your machine at all, download Malwarebytes (direct link in the rtf file in zip). Install and update Malwarebytes and run a full scan, all while still in Safe Mode.
Let us know how you get on.