Check ownership of the files, may have to be root to look / delete..

Try using the command line "ls -l" command.
Look at the file permissions and ownership, there may be some clues there.
You may be able to do an "sudo rm <filename> . . .

Just curious, what programs did you try and what was their output? Was the
locked folder generated by one of the programs and can you see how large it
is?

it was recup and photo rec
size is unknown Microsoft free zone.

If you are really sure you don't need these files just boot to a live CD,
find them and delete them. A live operating system doesn't respect file
permissions it hasn't created. Try puppy lucid 511, its based on ubuntu,
fast and quick to load.

You can change permissions and delete any file as root. To start the file
manager as root open a terminal and type: gksu nautilus [enter]. It will
prompt you for your password.

Note: you will be in the root home folder and not your own. Navigate to your
own home folder and you should be able to delete files that you could not
before. You can also change permissions as root by right clicking on a file
or folder and going to the permissions tab.