Try to make a new folder in windows and give it name con,aux,lpt1,lpt2,lpt3 up to lpt9. You won't be allowed to create folder with above mentioned names, because they are reserved words in windows.
How to create undeletable and unrenamable folders???
***Follow the steps***
Step 1: Open command prompt. Press Win+R, type cmd and click enter.
Step 2: Remember you can not create undeletable and unrenamable folder in your root directory (i.e where the windows is installed)
Step 3: Type D: or E: in CMD and hit enter.
Step 4: Type-
md con and hit enter (md - make directory)
Step 5: You may use other words such asaux, lpt1, upto lpt9 instead of con in above step.
Step 6: Open that directory, you will see the folder created of name con.
Step 7: Try to delete that folder or rename that folder window will show the error message.
***How to delete that folder***
Step 1: Open command prompt.
Step 2: Type D: (if you created this type of folder in D: drive) and hit enter.
Step 3: Type rd con(rd-remove directory)
Step 4: Open that directory and the folder will not appear because it is removed...