Hello Theas, and welcome to the Community! What errors, if any, are you getting when you attempt to download updates? Also, make sure you are following the steps in this guide to update your device: https://www.samsung.com/us/support/answer/ANS00077582/
As for not receiving messages, the first thing to try is switching messaging apps (if using Samsung Messages, try with Google Messages or vice versa, as these two are the most similar, popular, and compatible with your Samsung device). If you are still not receiving messages through the other app, I would try resetting your network settings. Follow these steps:
-Go to settings -Go to General Management -Reset -Reset Network Settings -Reset Settings
The last thing to try is a factory reset, which will be like a fresh start to your phone. Follow this guide carefully, and make sure to back up everything you can prior to performing it: https://www.samsung.com/us/support/answer/ANS00062029/
If the above troubleshooting hasn't resolved the behavior, it is recommended to contact your carrier, as there could be anything from a SIM issue to a network issue, and the carrier is responsible for such services.
