|"If"... you can boot up - preferably to safe-mode with networking....- then do so. Then disable system-restore option; after-which go to Trend.com and run their freebie Housecall utility. Run a "full" scan there. Once it's finished - anything it may quarantine - delete it. Then reboot again in safe-mode and if all goes well... reboot to normal mode...|
If you cannot boot even to safe-mode (with networking) as above then use a Knoppix or Ubuntu CD/DVD (Linux variant on a CD/DVD. Once that boots up then, as above, run a full Trend/Housecall scan. And again if by chance "quarantine" occurs locate/delete its contents... Then reboot system without the CD/DVD and see if it improves.
Once you can boot OK - re-enable firewall (if it's not already - and it ought to be enabled even now); update M$ Windows Defender - and if it's not installed then install it immediately.
Also install avast (avast.com) freebie anti-virus utility; and run a full scan with that too - once you have done the Housecall scan.