Re: why gallery stuck in samsung s2
First, plug the phone into your computer, find all the pictures and drag them to the computer. That will keep them safe regardless of what you do to your phone. (I'd make a "save" folder or something of that kind of name, then drag the folders from the phone to that folder, so the pictures remain in folders with the right name [since that's the "album" name in Gallery.)
Then reinstall the folder lock app and unlock all the locked folders. If you can't do that, you may have to rename the folders (from the PC, you probably can't from the phone - I usually just add x or 1 to the end of the name), then drag all the folders from the "save" folder on the PC to the phone, then delete the renamed folders once you see that Gallery can see the pictures (you may have to restart the phone before that happens). (The folders may be locked when you look at them in the phone, but the PC shouldn't have any problem seeing them, since it doesn't know about the locking.)