security cameras cant be viewed

Hi. I was not able to view the cameras (provision-isr) thru cellular remotely, only thru  Wi-Fi locally.  I was told I needed to set up a second DDNS ip address to access remotely.  I used the DDNS address from my NVR but it would not work.  So I tried using alternative DDNS addresses listed on the NVR. what a mistake! After that, even though I put back the original, neither the local Wi-Fi or remote cellular viewing works. 
now no vids appear, no device at all appears. I tried calling tech support, no answer. I tried emailing, no reply. 
my tech guy left the company. I have no idea what to do.  I am sure it must be something simple like a port number etc. any advice would be most welcome. I have apple devices