With the Winter ’18 release, Salesforce will no longer support Chatter Answers, and users of Chatter Answers will no longer be able to post, answer, comment, or view any of the existing Chatter Answers data. Customers will have until the Winter ’18 release to complete their transition to Chatter Questions.

Chatter Answers is a Questions and Answer (Q&A) feature that allows users to post questions and receive answers and comments from other users or support agents. The functionality is used within portals, Communities, or internally as a separate object within your Salesforce org.

NOTE: Chatter Answers is unavailable for new orgs created with or after the Summer ’16 release. Such customers will need to use Chatter Questions.

Check the below link for more information

https://help.salesforce.com/articleView?id=Chatter-Answers-to-Retire-in-Winter-18&type=1