If a keyword fails to trigger the display of your ads, it's possible that negative keywords are to blame. Negative keywords are used to prevent ads from displaying when certain keywords are used in search queries. The Blocked Keywords feature identifies keywords that conflict with negative keywords and allows you to review and remove the negative or positive keywords that are being blocked.
How to remove blocked keywords
Option #1: Workshop
Blocked keywords are identified via Targeting & Keywords notifications, specifically Blocked Positive Keywords. Use the Workshop feature to modify, pause, or delete these or negative keywords.
Option #2: Manage
You can also remove blocked keywords in Manage:
Go to Manage in the top menu.
Click on an account from the list.
Select the Tools dropdown, and choose Blocked Keywords.
Click the > icon next to the negative keyword to reveal the blocked content.
Select the checkbox(es) next to the keywords you want to remove.
Click Remove # Blocking Negative Keyword in the blue bulk edit menu.
This action will delete the negative keyword, and you will no longer be blocking it. The blocked negative keyword will be removed from all instances where it was applied. For instance, if your blocked keyword is a component of a shared set, it will be eliminated from any location where you've utilized that shared set.
Note: You can also see if a keyword is being blocked by navigating to the keyword section of an account. The status of the keyword will be bright red and read Blocked. Once the negative keyword is removed, the keyword being blocked will have a green status of Eligible.