Ok I don’t think you locked yourself out … whew!
You will need to specify the new port in your SSH command:
ssh -i ~/.ssh/id_rsa root@IP -p 7811
Now I recommend you follow this guide for how to disable root login - as you do not want to be running as root user:
I also recommend changing your SSH port again as you’ve posted it publicly, which somewhat defeats the purpose of changing the port):
Here is a thread to review as well:
Your friend, FROG