If you're trying to send a message on Facebook and it's not going through, there are a few things you can check:
- Make sure you're connected to the internet. If you're not sure, try opening another app that requires an internet connection, like your web browser.
- Check if Facebook is down for maintenance or is experiencing an outage. You can do this by visiting DownDetector or similar websites.
- Make sure you're using the latest version of the Facebook app. You can update it through your app store.
- Try restarting your phone or other device. This can sometimes fix simple glitches that may be causing the problem.
If none of these solutions work, it's possible that the person you're trying to message has blocked you on Facebook. If this is the case, there's not much you can do except try reaching out to them some other way (like by email or phone).