Replacing the router will not have changed any settings in the camera. The IP address 192.168.0.253 is the factory default for the camera, unless you assigned a new one when you set the camera up.
This is a wired/wireless camera, and if you're trying to connect wirelessly you probably have a router setup issue. Like any wireless device, the camera needs to provide the right key to connect. If you haven't set up your new router's wireless security yet, or set it up with a different key than the old one, the camera won't be able to connect. If the camera's not on your network, you won't reach it and you'll have the problem you described.
The simplest thing to do is to start fresh. Reset the camera to factory defaults with its rear-panel reset button. The button is recessed and you'll need a pen or other object to press it for a couple of seconds. Connect the camera to the router using a cable, and you'll be able to reach it again on 192.168.0.253. Set up the wireless network in your router (assign network name, security key, etc.). Then go through the camera wireless setup steps so it can connect to your network and you'll be back in business.
If you need a copy, you can download the manual and find other information here