If the extension is not displayed for user-specified (or default) settings, there are several ways to determine the file type. The simplest of them: move the cursor to the file icon and wait a few seconds without pressing the button. POPs up a small window with brief information. Among other things, this tooltip will indicate the file type.
Refer to the file properties, if information is missing. To do this, move the cursor to the icon of the desired file and click the right mouse button. In the drop-down menu, select "Properties". This will open a new dialog box, navigate to the General tab and read the information you need in the field "file Type". If you accidentally opened the properties of the file and the shortcut, on the General tab you will see the type "Shortcut". In this case, go to the tab "Shortcut" and read the data in the field "object Type".
You can also customize the display of file extensions. To do this, open "control Panel" via the Windows key or "start" button. Select the icon "folder options" in the category "appearance and themes". Alternatively, you can open any folder on your computer and select in the menu "tools" the item "folder options". When you open a new dialog box, activate the tab "View".
Scroll down the list under "advanced settings" and find "Hide extensions for known file types". Remove a token from this field and apply the new settings. Close the dialog with OK button or icon [x]. File extensions will be displayed.
In some cases, even with proper settings, the file extension may be absent, and in the properties window in the field "file Type" will be the definition of "File". You can try to open the file in different applications, it is likely that one of them will fit.
Another option: click the right mouse button and select "Open with". From the list of programs, select a simple Notepad. Regardless of the encoding in the beginning of the text can contain information about the file extension or the application in which it was created.