LOCK/UNLOCK COMPUTER WITH PENDRIVE

Just follow the steps as given below :- 
Insert your USB drive into your system and wait for it to be recognized..

STEP1:-Go to Start >
Control Panel >
Administrative Tools >
Computer Management >
Disk Management >
Or
You can go directly by typing the command in run: diskmgmt.msc

 Then right-click the partition whose name you want to change (click in the white area just below the word “Volume”) and select “change drive letter and paths.”

From here you can re-assign the drive letter it was given to “A”
NOTE:Drive letter of pendrive must be "A"

STEP2:- Start->Run->syskey

click on "ok"

Syskey launched: Click “Update”

Choose “Store Startup key on floppy disk” and click “OK”

You’ll be prompted to enter your diskette. Make sure your USB drive is inserted and writable.
Restart and have fun. Don’t lose your USB disk! Also, to revert this, you can run syskey again and choose to store it locally instead of “on a floppy disk”.

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OPEN CMD WITH RIGHT CLICK.

Just hold down the Shift key and right-click on the desktop…

And then you can choose “Open Command Window Here” from the menu. The great thing about this is that the current path is the desktop, which is convenient for manipulating files on the desktop.

Of course you can always right-click on any folder icon in the system while holding down the shift key:
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HOW TO CHANGE DRIVE LETTER.

To change drive letters ...
Just follow the steps as given below :- 
Go to Start >
Control Panel >
Administrative Tools >
Computer Management >
Disk Management >
Or
You can go directly by typing the command in run: diskmgmt.msc
Then right-click the partition whose name you want to change (click in the white area just below the word “Volume”) and select “change drive letter and paths.” From here you can add, remove or change drive letters and paths to the partition.
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HOW TO HIDE TEXT BEHIND IMAGE(STEGANOGRAPHY)

What is Steganography?
Steganography is the technique of hiding confidential information within any media.

Just follow the steps as given below :- 
First copy any Image to your C: directory
Open cmd by going Start-Run program- type cmd (Administrative mode)

Type command cd\ in cmd press enter.
Now write command as:
echo “your text to hide” >> image.jpg
change 'you text to hide' to your message and also name of the image.

 Now go to your image and open it with Notepad and you will your hidden message at the end of the image file contents.

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