If you want to unlock a folder or a file using command prompt then just follow below simple steps.
1) Go to Start > cmd and press enter.
2) Now in the command prompt write this command Attrib -s -h (path of the file).
3) For example if I want to unlock the folder named as “aaaaa” which is located in D: then I will write this command Attrib -s -h d:\aaaaa .
4) By doing so aaaaa folder will become visible in your D: