It would help if you posted more about your setup, any changes you might have made, why you thought the command you ran would solve the problem. At the bottom is a link to guide you to providing more information.
In the mean time, did you run out of space on your elasticsearch server? Have you checked the Graylog logs and the elasticsearch logs?
tail -f /var/log/graylog-server/server.log
(Elasticsearch is whatever you called your instance located in /var/log/elasticsearch… possibly graylog.log)
Don’t post the whole log, just parts that are relevant - and please use the forum tools such as </> to make your code/logs more readable. Also review below for help on giving good information when asking a question. 