10) How to lock a folder without any software?

Follow these steps.
1. Suppose you have a folder named abcd in D:\abcd.

2.In the same drive next to the folder create a new notepad file with the exact statement
ren abcd abcd.{21EC2020-3AEA-1069-A2DD-08002B30309D}

3.Now save this text file as loc.bat

4.Create another notepad file and type
ren abcd.{21EC2020-3AEA-1069-A2DD-08002B30309D} abcd

5. Save this as key.bat

6. Now there are two batch files . Double click loc.bat and your folder will change into Control Panel and its contents cannot be viewed.

7. To open the folder double click key.bat and you get back your original folder .

8. For more safety keep the key.bat in another location .Only for unlocking copy paste to the original location and double click .

If you combine this with the hidden folder trick, it will be impossible for anyone else to access it .