I have recently started using iptables, and I executed iptables -F without knowledge of what it might do. And suddenly I have lost connection to the node. I can't even ping the node. Any help would be highly appreciated!
iptables -F will have flushed (deleted) all of your rules, I guess your input policy is DROP so without any explicit ACCEPT rules you're locked out. Your best bet is to reboot the node and cross your fingers.
You flushed all your iptables rules, including the default ACCEPT. You'll need to either reboot the server (and hope that it loads up a proper set of rules) or get on the console and fix it from there.