Can I log into Messenger without the app?
The best workaround for how to access Facebook Messenger without the App is to use the full desktop version of Facebook. Go to https://www.facebook.com/home.php for the full version. It isn't mobile friendly, but at least you'll be able to access and respond to any messages in Messenger.
Can you download Messenger Lite?
Free lightweight Facebook messaging app. ... Due to Messenger Lite being a substantially stripped-down version of Facebook Messenger, it can run on older versions of Android and works seamlessly even on 2G networks.