I accidentally opened a file with a specific program and now all of them that are similar have different icons and won’t open properly. I don’t know how to return them to default. What can I do?
You may again choose default program, just right click on the file click on "openwith" then "choose default program". Now you may pick your favorite program.
If you want to restore the default Windows behavior for those file types, you can use Unassoc to remove the current association and have Windows revert to its default behavior for that type. If the association is handled by software other than Windows, you will still need to reset the correct association to that software by either using the Default Programs option or by going through the entire list of types to reset each affected type yourself.
Without file type it is a bit difficult to say...But if it is music file or documents, then simply go to that file and right click on it and take your mouse to "open with". You will see the programs available that can open the particular file.
If it is an unknown file, then right click and choose open. You will see a pop-up mentioning "windows can't open this file". Go down and choose "Select a program from a list of installed programs" and click "ok".
Even if you have selected a particular program you can do this to change, but if you are not sure uncheck the option "Always use the selected program to open this kind of file".
This is a general answer. To be specific please mention the problem in details like type of file and how it has been done.
It's a shame you didn't mention what kind of file it is. With some files (e.g. mail and web related ones), you can reset the association by using the "Default Programs" option in the Start menu.
With others (most document types, for example), you need to follow Saumyakanta's advice, i.e. right-click on the file, choose "Properties", click on [Change...] at the top and select the editor you want to use. If it's not listed in the Window, click [Browse..] and find the editor's .exe file. For example, I use VLC for playing movies, so if I wanted to associate movie files with it, I'd navigate to C:Program Files (x86)VideoLANVLC and choose "vlc.exe".
If you're not sure where the program you need resides, or what the .exe file is called, reply on this thread with details of what program it is, and we'll do our best to help you (it would also help if you tell us which version of Windows you're using).
Open the property of that file , In the general tab see for "Open with" and change the program selected.
perhaps you have file association problems, if you have windows restore point use it to revert back just before the problem.
How To Change & Fix Broken File Type Associations In Windows 7