I had down loaded lock file software from mobile9.com site. On running the application it is not asking security code. I can hide and unhide files without any security code which is of no use as any one can unhide the files and tamper with the file I wanted to hide. Can any one help. My hand set is Nokia c-3 00.

to unhide file extensions to see what you have in XP open my computer (or windows explorer) Tools/Folder Options/View change 'Do not show hidden files and folders' to 'Show hidden files and folders' uncheck 'Hide extensions for known file types' if you wish you can uncheck 'Hide protected operating system files'

to unhide file extensions in win7, vista go to my computer (or windows explorer) Organize/folder and search options/view change 'Do not show hidden files and folders' to 'Show hidden files and folders' uncheck 'Hide extensions for known file types' if you wish you can uncheck 'Hide protected operating system files'

In win8 I'm not sure how to get to it unless you change to show classic view somehow

Sometimes is hard to open a hidden file, I must unhide from you app you have used. I suggest you this applock, it can help you to hide your stuff, lock apps, track phone and more.
LEO Privacy Applock Boost Hide Android Apps on Google Play

You can try this app here, it is convenient to hide the file you want and lock the app you want. Besides, it can also give to your Android better security by browsing (private browser) and clean the RAM of your phone (boost). Just try it.
LEO Privacy Applock Boost Hide Android Apps on Google Play

As a default sony ericcson doesnt provide any such module or application to lock the folders. But still Java softwares are available in internet in JAR format.
Download this JAR file from internet & store it in your mobile memory card & then install it in your phone.This application will help you to lock the folders or files.

just go to getjar.com here you will find my file manager who can hide the file or a folder

If you would like to hide or secure your files from prying eyes, there are plenty of java applications available to lock them. Lock It Down is one of them

video seeking is not supported with 6233.
Some file manager applications are available at getjar, mobile9 and mobiles24 can hide files so just try them out. I am using mobyexplorer, and it can hide files and folders.

since it is a java base mobile you can not lock your folders . folder lock softwares are also not supported in 3110c

sonyericsson.com

THERE IS SOFTWARE NAMING FILE PROTECT ON WWW.MOBILE9,COM