Normally we find that we will be able to open a single type of file with multiple different programs, so within the operating system we can find it in the Launch Services section, from which all file associations will be grouped for later use. When installing a new program, Launch Services will make that the default program or, on the contrary, it will leave it as an alternative to, as I have said, open a certain type of document or file.
We would have an example in files with .pdf extension that in OS X by default is programmed to open as Preview, however we can download a third-party program such as Adobe Reader and make it the default easily with the option Open with> Other and checking the box Always open with this app.
But sometimes everything does not go well and some associations are made incorrectly and are poorly reflected within Launch Services. When this happens it is possible that even if we change the program, the error persists and does not finish opening with the one we want, showing us duplicate entries of the program in question in To open with, error messages or that directly tells us that there is no program or set of programs to open that file extension.
If this happens, the easiest method to get everything back on track is to clear the Launch Services database with the information of the stored programs, for this we will open the terminal and execute this command that will reinitialize these associations to those of by default (the accent to use is to the right of the P key):
sudo `find / System / Library / Frameworks -name lsregister` -kill -seed
With this command the extensions will not be disassociated to the corresponding programs, but it will fix the errors or entries that could be wrong giving problems.
More information - Change the background of the notification center in OS X [Part 1]
Source - Cnet