How to retrieve message requests on Instagram

It all depends on what Instagram has stored on its servers. It seems the easiest way to ensure you can always recover your messages is to download your data regularly so that, if they do get deleted, you have a backed-up copy on hand that you can look back on. Luckily, it's exactly the same process.

If they accept it, your message will enter their main inbox — and you'll be able to see whether they've opened the message. However, if they delete it, or choose to leave it lingering in their message requests, you'll never be notified.

Messages from people you follow on Instagram will appear in your Chats list. You can choose who can add you to groups.

The message author has deleted the message, or their account has been deactivated; The 4 weeks since the message was sent have passed by and then the message gets automatically deleted (something I have noticed that Instagram does).