Magento 2 changes in Js and CSS
step 1. delete all folders under pub/static/frontend
step 2. delete cache folder under var/cache
Now open your command prompt and go to your root installation of magento 2 and fire the following commands
step 3. php bin/magento setup:static-content:deploy
step 4. php bin/magento indexer:reindex
The above step worked for me. I hope it will work for you also.
Let me know if you still facing any problem.