There could be many reasons, I recommend having a look at the following policies:
The most common issues are:
You can ask Google for specific examples of policy violation. To do so ask here and check the box, I need more info : https://support.google.com/merchants/contact/suspended
Hope this helps.
Under my name, you see my website, click on it and then you will see a contact link in the header of my website.
Thank you for your interest in contacting me.