First of all...never test thing on production environment...never. I have 3 ESXi 4 servers, two of them on vDS switches and one on old fashion virtual standard switch. When I moved third one to vDS and after assigning vmnic's to appropriate dvPort groups I had problems with connectivity...so because it was urgent (Production), I decided to bring all back to vSS just for this one ESXi 4. If you make mistake and remove physical NIC from vDS you may lose management connectivity to server at all...which is bad. But here are some useful comands which you need to enter directly on ESXi console to restore basic connectivity and after that everything else in your environment:
alt+F1, to access cmd line interface on ESXi
type unsupported with your admin password
From cli now you can see your curent configuration:
esxcfg-vswitch -l, list your curent DVSwitch, DVPort and vmnic names (if output after this cmd is to big and you can't see what you need use | grep or | less or | more options),
esxcfg-vswitch -Q vmnic0 -V --dvport --dvSwitch, to unlink vmnic0 from vDS
esxcfg-vswitch -L vmnic0 vSwitch0, link vmnic0 to vSwitch0
After this, you have your basic connectivity back and now you can proceed with vSphere client to finish everything you need...optionally, you could check you default gateway by editing /etc/sysconfig/network or adding default gateway with route add default --gateway address.