First, Force quit Finder. You can do this by pressing the <kbd>option</kbd>+<kbd>command</kbd>+<kbd>esc</kbd> keys and then selecting Finder from the list and clicking on the <kbd>Relaunch</kbd> button.

Then, try deleting the Finder's preferences file: com.apple.finder.plist, found in ~/Library/Preferences. 

    rm ~/Library/Preferences/com.apple.finder.plist

This file seems to easily become corrupt. Trashing it is a good first step when Views become wacky—anything to do with Finder.