Find your chrome version (Help-> About Google Chrome)
Find your chromedriver version, if you already have one. (For me "chromedriver.exe -v" gave me the version on windows environment.)
Visit the official chrome webdriver page (http://chromedriver.chromium.org/downloads)
Download the chromedriver matching your chrome browser version, from the above download location.
Have a glance at the release notes on this download page towards lower section of the page, which gives an clear idea regarding which driver to use for which version of browser.
You can put the downloaded chromedriver binary in the path environment.