Readynas NV+ v2 network issue

192.168.168.168 is the default if the NAS does not get a DHCP address, so a dead LAN port would have that result.  Do you see any activity on the NAS or switch LAN port LEDs?  Can RAIDar find the NAS?  I've seen ports get "weak" and not woprk with certain "green" devices, but yours not working when directly connected to a computer with an appropriate IP address pretty much says that's not it.

If you are seeing LED activity, it could be an OS issue and you can try an OS re-install.  But if you see nothing, not even as it boots, it is likely dead.

There are some options for recovering your data if you don't have a backup.  All will require you have some place to offload the files unless you want to buy a (very old) used NV+V2 and just move your drives to it.  Those methods include connecting the drives to a PC (all of them together) and using a Linux Live CD or R-Studio for Windows or purchasing a new OS6 ReadyNAS and using it for recovery (with some help from Netgear).

Just make sure your NAS and the one you buy are "real" V2's (or V1's).  The V2 says so on the front and has an external supply.  There are some V1's around that have a small "V2" on the siticker, but they are still a V1 by the current nomenclature.