When you enter your droplet from DigitalOcean’s console, can you try and start your network. It’s possible something is interfering with it on boot. That’s going to be my best bet!
Additionally, when you try and SSH to your droplet does it show an error like
ssh: connect to host ***.***.***.*** port 22: Connection refused.
Or is it completly unreachable. If it’s unreachable try the first method I described. If it gives an error like the above one, I’ll recommend the following
ssh -v [username]@[ipaddress] ....
ssh -vv [username]@[ipaddress] ....
ssh -vvv [username]@[ipaddress] ....
What this does, essentially, is increase the verbosity of what is output when attempting to connect via SSH. This will give you an idea of what’s going on during the back and forth exchange. Start with -v, then -vv and finally -vvv (as -vvv will throw about a page and a half of output at you).
You can also check /root/.ssh/knownhosts (on your local machine - if using Linux). You can clean that specific file out and then attempt to reconnect. It’ll ask you to confirm that you’d like to add the host you’re connecting to (to the knownhosts file). I’ve had plenty of instances which required this over the years as small changes (regeneration of server keys, for example), can invalidate your connection (though you’ll normally receive a message in such a case).
Beyond that, was a firewall active (i.e. iptables or UFW)? If so, and your IP wasn’t whitelisted, it’s possible your connection is being blocked. You should still be able to get in through console though.
Let me know how it goes