I can't un-checked the "Hide extension for known files type" on tools - folder options - view.

1. Start Windows Explorer, you can do this by opening up any folder.
2. Click Organize.
3. Click Folder and search options.
4. Click the View tab.
5. Scroll down until you notice Hide extensions for known file types, un-check this line by clicking the check box. ...
6. Click OK.

Start....Type Folder options in the search box.
Select the View Tab
Then select the options you want to view.
Uncheck the box for "Hide extensions for known file types"

Caution. Be careful when displaying protected operating files and hidden files.
They are hidden for a reason, and if you are operating from an account with administrator privileges (Not a good idea for day to day stuff) you can cause carnage by deleting or modifying some of them.
Paul

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

You have to check the exstension, to do this follow these steps:

1. In Windows 2000 or Windows XP open My Computer
2. Click Tools
3. Click Folder Options
4. Click View tab
5. Uncheck the box that says Hide file extensions for known file types.

Or

1. In Windows XP click on Start
2. Click Control Panel
3. Click Folder Options
4. Click View
5. Uncheck Hide extensions for known file type.

If you want to shot/cut your file, you can use freeware tools - Audio File Cutter

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 to see what you have in Vista open 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'

if this is what you mean

What do you mean by only certain files? from photo's?
Its possible they are hidden files.
Go to tools then folder options. then view
In the hidden files and folders section set it to show hidden files and folders. and take the check mark out of hide extensions for known file types and hide protected operating system files. check for your files after that.

Once you have it off I would suggest changing those settings back.

Hi,
try to change the file extension of the pictures.
go to folder options > view > un check hide file extensions for known file types
click aply and OK.
then rename the file extension. put it as JPEG.
then try to open it.

You have to make sure you click the "apply" button before exiting otherwise windows reverts to your last saved configurations. Hope this helps

If you want to change the extension of an existing file type, then open any window, goto->tools-> folder options->view-> uncheck the option that says "hide extensions for known file types". Once you do that you'll get the filename with extension.You can necessarily change it accordingly.

By default, file extensions for known file types are hidden in Windows XP. However, you can change this setting so that file extensions are shown for files in a certain folder or for all files on your hard disk.
To show file extensions, first open any folder on your hard drive, such as "My Computer" or "My Documents." Then select "Folder Options..." from the Tools menu as shown below.
When the Folder Options window opens, click the View tab. This will show the file and folder view settings.
One of the options under Advanced settings is "Hide extensions for known file types." If this option is checked, uncheck the checkbox and click Apply or OK. This setting is system wide, so unchecking this box will make file extensions appear in all folders.
If you decide to hide file extensions at a later time, you can check the box again and click OK to revert back to the previous settings.