Is it everyone else's avatar as well?
This is normally caused by blocked or lost traffic. Are you using a public network? If so, somethings probably fucked with it, public networked are susceptible to these issues, or the traffic may be "intentionally" blocked by whoever owns the network.
If it's a home network, it could be a temporary issue with your ISP. However you can try these local fixes to see if it's not something you can do on your end.
Make Sure nothing is being blocked in your firewall;
Restart Computer, Router, Modem;
Release and Renew IPConfig, Flush DNS