"show in finder" open the file instead of opening the directory containing it the problem appeared after i tried path finder app, i didn't like it, i removed it using cleanmymac, than i used 

defaults write -g NSFileViewer -string com.apple.Finder

and
 rm Library/preferences/com.apple.finder.plist

now every time i click on show in finder, instead of opening the folder containing the file( the default behaviour of finder), it open the file, for EXP: if the file is a dmg it mount it, if it's a text file it open it on an editor, would any one have any idea how to reset finder
I don't know if this will solve your problem but to reset Finder you should relaunch it. To relaunch the Finder, hold down the option key and right-click on the Finder icon in the dock. A list of options will appear. The last option is Relaunch. Click that and the Finder will relaunch.

To relaunch from the terminal: open the terminal and type: 


  killall Finder


'