The only thing I can think is that the router itself was reset back to factory defaults. The network "dlink" is the standard wireless network name that D-Link delivers with most of the DIR routers.
You will have to re-do the router's configuration again. This time, "save" the configuration to one of your PC (for use to restore the router the next time.) Also, make sure that you change the router's "admin" password since the password is the "default" one used on all D-Link DIR routers and a lot of "hackers" try to access routers remotely so as to "screw you up."