I was trying to update the software on my D-Link DIR-615 router and downloaded the update on the D-Link support page. It downloaded a .bin file. By referencing the Support site I was eventually able to figure out how to update my router's software. Unfortunately, at the time I downloaded it I did not know I was not supposed to open the .bin file. So, when I double clicked on the .bin file and nothing happened, I stupidly designated a program change under "Properties" and changed it to have the program "NOTEPAD" open the .bin file. I have subsequently figured out how to use the .bin file to update my software. My problem now is that because I changed the .bin file to open using Notepad, no matter how I try I can't change it back to a .bin file. This includes deleting it and downloading it again from the Support page; every time I download it, it still SHOWS up as a Notepad file and not a .bin file. I hope you understand my problem and can help. Thank you.Changing the program it opens with doesn't change anything about the file itself.

What you've run into is Microsoft's bone-headed, but well-intentioned decision, starting with Windows 95, to hide File extensions. What happens is basically if Windows knows how to open a file, it won't show the extension at all, OTHERWISE, it will.

The dialog you saw basically sets the association, so from that point forward, Windows knows how to open the file, so it is presented without a file extension. ADDITIONALLY, the icon will change to show a little image of the associated program inside the default page.

The "fix" is effectively to do nothing- nothing about the file is changed, it merely opens with notepad by default. You should be able to right click on the file and select a new program to open it, or deselect the BOX that says to use the existing program or app to open all files of this type.