Google Ads on Twitter has mentioned that they will be automatically deactivating accounts that have no spend in the past 15 months. The good news is that you can reactivate your Google Ads account at any time.
Google Ads Cancellation of Inactive Accounts
When your account is deactivated, you will receive an email notification that your Google Ads account has been canceled.
If your AdWords account has been inactive for more than 15 months
(meaning your account hasn’t spent in more than 15 months)
your account will be automatically cancelled.
Note that there are other reasons an account can be automatically cancelled.
You can read more about the cancellation of inactive accounts on Google AdWords Help.
Google Ads Reactivation of a Cancelled Account
You can reactivate your Google AdWords account by simply signing in and reactivating it. However, if you continue to have no spend in the next 3 months, then your Google Ads account will be deactivated again. If you canceled your Google Ads account on accident, you have 2-3 weeks to recover it.
You can find out more information on reactivating a canceled AdWords account in the Google Ads Help section.
If you need help reactivating your Google Ads account, you should contact Google or a highly experienced Google Ads PPC company that has a Google Partner relationship.