First things first. Google isn’t going to specifically say why:
“To protect our proprietary detection system, we’re unable to provide our publishers with specific information about the violation, including specific web pages, users, or third-party services that might have been involved.”
But Google listed the reasons that could lead to your account getting banned. As a publisher, your first step is to figure out why it got banned in the first place.
– Segment your traffic sources and analyze how the users from each source performed over the last 60 days. Especially, if you have paid traffic acquisition sources, then you need to scrutinize the data and see if something invalid shows up.
– Ad performance data. The next thing is to analyze the performance of ad units/orders/demand partners and find anomalies (if there is anything).
– Check whether you have implemented any pop-ups or pop-unders or the ads are obscured under the content/navigation.
Once you figure out why it’s time to fix it. Your account might be disabled for more than one reason, so it’s better to be thorough. If you are certain that there are no holes left, then appeal using this form.
Please note that Google wouldn’t allow you to appeal again.