If you find yourself without a network connection at this stage, don't panic.
Assuming you are connected via ethernet on eth0 (default 1st network card), the following will get your network device reset:
sudo ifconfig eth0 down sudo dhclient -r eth0 sudo ifconfig eth0 up sudo dhclient eth0
That should have you up and running again with a wired connection. Obviously, if you're using a different interface, just substitue eth0 for whatever your interface is called.