Step 1: Press Win+R to RUN and type CMD in run and press enter.
Step 2: When the console is open type commmand 'TASKLIST' (without quotes) after that you can see the list of all process with their PID(Process ID) which is run over the system.
Step 3: For terminate any process you need to type command TSKILL with their PID(Process ID)
For example according to above image if we want to kill the windows media player then the required command is TSKILL 3964
Tip: If Cmd is also not open due to virus or any other reason then type COMMAND in RUN .