That generally indicates that there was a typo in the statically assigned address or gateway, which inadvertently ended up with the cameras being on a separate subnet from the computer that you are using.
If you have an NVR, you might be able to force a reset by factory resetting the NVR, but be sure to disconnect the cameras that are functioning normally.
What is the current firmware version of the cameras? For most cameras, we recommend against statically addressing the cameras. For static network configurations it much easier to set static reservations in the router than on the cameras.