In some cases, Facebook will disable accounts that don't follow their Ad Policies or Terms of Use.

If your ad account has been disabled for not following Facebook's Advertising Guidelines or Terms of Use and you believe this was disabled by mistake, fill out this form to initiate an investigation and hopefully reactivate your account > https://www.facebook.com/help/contact/2026068680760273?helpref=faq_content

f you were notified that your ad account was flagged for unusual activity, you can initiate an investigation through this form > https://www.facebook.com/help/contact/531795380173090?helpref=faq_content
You can also go to your Ads Manager, and follow the instructions in the red box at the top of the page.