How to Lock a Folder without any software

There are lot of methods for locked folder, most of which require use of some third party software. There is another way to create a secure locked folder without having to buy any third party software.
Here are the steps to create the  protected folder in windows xp:
First create a folder that you will use to store your confidential data. For example, I have create a folder called New at the root of my D drive.

In the same location where you create the new folder, create a new file in Notepad, copy the following below into it, replace New with the name of your folder and save it as "loc.bat".
ren New New.{21EC2020-3AEA-1069-A2DD-08002B30309D}

Now you should have a bat file name loc.bat in the same directory as your New folder, not inside the New folder.
Then create another Notepad file and type in the following listed below and save it as "key.bat".
ren New.{21EC2020-3AEA-1069-A2DD-08002B30309D} New
Now you will have loc.bat and key.bat along with your folder. Go ahead and double click on lac.bat and your folder will turn into the Control Panel and nothing inside can be viewed. Clicking on it will simple bring you to the Control Panel.

To view the data inside your folder again, click the key.bat and your folder will return normally.
Of course, keeping the key.bat file in the same folder will defeat the purpose of securing the folder, so it's best to move the key.bat file somewhere else, or even better, put it on a USB stick or hidden that only you can access.