First, check to see if the bot's status is not offline. If it is
offline, it is likely an outage. Second, make sure you are using the
correct prefix. The easiest way to do this is to replace your prefix
with the bot's mention. Third, check to see if the bot has permission
to read messages in the channel and send messages in the channel. If
it is still not working, and you would like to rule out any
permissions issue, you can temporarily give the bot the Administrator
permission. If it responds after that, then it is a permission issue.
(don't forget to remove this permission after testing!) If none of
those have worked, please join our support server and ask in the
support channel. Don't forget to mention you have tried all of the
above steps!