You can reset the passwords using SADP
http://overseas.hikvision.com/ueditor/net/upload/2015-12-24/b7d67cfb-e66d-477a-ae71-ec751d86da85.pdf
Follow the instructions depending on which cameras you have and email Tech Support
You need to connect your laptop/computer LAN port to a camera port on the NVR and configure the adapter to use the the same network as your cameras for SADP to see them (see post 4). I had to reset all the passwords on my cameras to get them working again.
I have received a reply, but unfortunately hasn't solved my problem. Perhaps you would like to try to see if I'm doing anything wrong. Connect your computers LAN port to a camera port on NVR and configure a static ip address on your computer to the same as the cameras, making sure it doesn't...
Can't help, but I have the same problem. I have emailed Technical Support and if they come up with an answer, I'll let you know unless someone else can help.