If your ads don’t get impressions you should try to increase your target cost.
Navigate to the Ads view under the ‘My Campaigns’ section. Select the ad that doesn’t get impressions and click “Bidding” in the bottom toolbar. You can update your bid by typing a new value in the target cost section and pressing ‘Update’.
Please note that you're only able to update your bid if you're using 'Lowest cost with cap'.
If you have already updated your bid or if you're using the Target or Lowest cost optimization, please make sure you haven’t reached your spend limit on Facebook. To see or change your spend limit go to the “Billing manager” in your Facebook Ads Manager. Read more about ads delivery in Facebook’s help documentation.