Why was my Google Adwords Account suspended?

There are reasons why your account might be suspended. One of the most probable reason would be the violation of their Policy. Do review the link for you to see the rules stated by Google.
They are checking the relevance of the details in your campaign to the ugly site created and the details of your Ads which is why it is important for all details to match one source to another.
There are other rare instances when Google will suspend an account due to malicious activity on the account or when they implement an update on all Google Ads accounts, hence may lead to suspension as well.
If you are sure that you did not violate their policy, fill out the appeal form here: https://support.google.com/google-ads/contact/pf_suspended
And it is best to contact Google support after submitting the form to request to expedite the process in reactivating your account.
 FYI: Google AdWords Telephone Number: 1-866-2GOOGLE (1-866-246-6453) (USA)
Support Operating hours: 9:00 am - 8:00 pm EST Monday – Friday