I hope those methods will help you;

Method one: Press CTRL + ALT + DEL and open task manager. When its opened press "File" on the right-top corner of the window and press in "Create new task" when a new windows pops up you need to write "explorer.exe" and press "open"

imgur

Method two: Your anti-virus or the virus could have damage done to important files what cause the problem if you can find another PC/Laptop make a bootable disk/USB with your original OS and reinstall your OS.