Make a rescue disk from one of the anti-virus vendors, Avira and AVG both have them to download. Boot off the disk and follow the directions to run a scan. Malwarebytes is good for this also, but you need to download the setup and manual update files on another computer since yours probably now blocks access to the Malwarebytes web page. Stick the setup for it on a USB drive, and run it on your system in safe mode, then run a scan with it.