Google has officially deprecated their AdSense plugin for WordPress this month. It is no longer available for new publishers to sign up for. So if you want to use it on a new blog or you are new to AdSense, you need to find a different plugin. On April 5, 2017 existing publishers will not be able to change their ad settings or ad units through the plugin. Then on May 3, 2017 Google will no longer provide support for the plugin. Google said "We frequently review our products and features to ensure they're providing maximum value to our users. After reviewing the AdSense Plugin for WordPress, we've decided that going forward we can better support WordPress publishers through new innovative features like our automatic ad formats and other upcoming initiatives." Sources: Search Engine Roundtable
I found it through wordpress.org/plugins/tags/adsense-plugin but they will have withdrawn it. The quick start button on their email takes you to https://support.google.com/adsense/answer/7171740
Knowing the WordPress community and the variaty of plugins, this is not a huge loss (there are plenty of good alternatives to the plugin). Still, it was good thing knowing that Google officially supported it while it lasted.
I just thank to Google for closing this Junk AdSense Plugin, it's really worthless & just creating bad image of Google. I have used it more then one year ago for only 7 days, and I admit I have lost my 40 to 50 percent revenue because of this plugin.