Here are some steps you can take to know if someone blocked you on Instagram:

1. Search for their account. If you can't find it or see their profile image, you may have been blocked.
2. Try reaching their profile by tapping their name in messages. If you can't, they have likely blocked you.
3. Check your notification feed. If they were previously following you and now they are not, they have most likely blocked you.
4. Check their public posts. If they make comments or share posts from people who follow you, you are not blocked.

I hope this helps! Let me know if there's anything else I can help with.