The dedicated or VPS server you're on from HostGator seems to be either offline or unresponsive to external pinging. A traceroute also shows that the routing drops at the end-point, meaning your server.
Code:
# ping 174.121.97.109
PING 174.121.97.109 (174.121.97.109) 56(84) bytes of data.
^C
--- 174.121.97.109 ping statistics ---
6 packets transmitted, 0 received, 100% packet loss, time 5018ms
rammieone is correct, you'll want to contact HostGator's support team (assuming your domain registration is the same as your host) and ask them to resolve the issue.