The 1st step on discovering an infected machine is to isolate it from your network.
That means unplugging network cables and/or disabling Wi-Fi.
If you are using an unsupported Operating System and/or browser your computer and network are at risk.
WIPE & RESTORE MACHINE
If malware takes more than a couple of hours to remove it’s time to wipe the drive and start over. The big question then becomes what data I need to retrieve 1st.
If this machine use an outdated Operating System then it needs to be upgraded anyway.
Upgrade Outdated Operating Systems and Applications
When Operating Systems and applications lose extended support they are no longer patched for security issues. When they lose regular support they are no longer get upgraded features.
Sometimes malware will prevent you from even using your browser and re-direct you to fake security screens.
It’s probably best to run anti-malware from Safe Mode with network anyway so just reboot your PC and hit F8 as it starts up.
If you still can’t download a removal tool you may need to download on another PC and copy to USB drive.
Malware Bytes has a good track record for removing malware but you may want to check the Internet to see if there is a specific removal tool required for your specific malware.
You should download the updates for your malware removal program and run multiple times until everything comes up clean.