This means you do not have the Manage Server permissions for that server.
Ask an Admin or server owner to grant you the permission, or ask them to invite the bot.
Check the user list to see if the bot is showing offline.
If it is then join our Support server and report it so we can get it restarted.
If it is online but wont respond to commands, then make sure it has the following permissions:
Send MessagesEmbed LinksRead MesagesManage Messages