how do i open files with windows shell common dll?

[borgatron]

earlier today i was fiddling around trying to make a file work properly for a game and changed what program i used to open it. I kinda wish they'd mention that by doing so, you're now stuck using that as your default file opener. i tried to find windows shell common dll (the usually program), but i can't find it. anyone know the problem?

[techsent]

whats the name of the file?
whats the version of the file?
whats the created date of the file?
whats the last modified date of the file?
in what folder is the file located?
whats the name of the game?
whats the version number of the game?
why did you need to fiddle with the file?
is this game compatible with the version of windows installed onto the computer?
does your video card have the necessary features to play this game?
what are the specs of your video card?
have you over clocked your video card?
have you over clocked your cpu?
how long have you been playing this game?
what version of directx is installed on the computer?
whats the name of the sound card that is installed on the computer?
what are the driver file version numbers of the video card and sound card that is installed on the computer?
what are the names and version numbers of other programs that are actively running on the computer?
has this problem ever occured before? if yes, when and how often does your problem happen?
what version of windows is installed on the pc?
what is the service pack number for the version of windows that is installed onto the computer?
is the version of windows 32 or 64 bit?
whats the name of the program that was changed too?
whats the name of the windows shell common dll (the usually program)?

When you reply to my questions, be extremely specific in your answers!