it depends, with folder lock there are three levels of security
lock simply hides the folder, you can still access the folder if you have show hidden files and folders enabled
scramble scrambles the file, i believe it splits the file somewhere around the middle and mixes the first and last halves
encrypt is almost unbreakable, depending on your password, it encrypts your file using an algorithm, in which it inserts your password) so that not even folder lock knows your password, folder lock takes the password given to it and attampts to unlock the folder, if it can read a special file inside the folder, its unlocked, if it cannot read the file inside the folder it reverts and tells you you got the wrong password
after re-install my PC ,when i open folders protect “USB lock AP” software ,error is display “This folder can only accesed by its owner while inside the PC in was protected”.Who can give me to solution
I don't know about newer versions of folder lock, but older versions relied on a rootkit. As such, folders were hidden only when accessing them from that machine and that OS. Folders and files were available if accessed from another machine (on the network) or by booting another OS such as a Linux liveCD.