First item......the Time Capsule needs to connect to your router using a permanent wired Ethernet cable connection, so that would be the first requirement if you want to try get the Time Capsule working again.
It would help if you could provide the make and model number of your router, so we will have a better understanding of your network devices.
Would also help to know what model of Time Capsule that you have. If your device looks like a small white pizza box, look on the bottom of the device for the model number, which is usually embedded in the foam pad base. The model number starts with an "A" followed by 4 numbers. Please do not provide a serial number as that is not needed......just the model number.
If you have the more recent "tall" or "tower" shaped model of the Time Capsule, just indicate as such.
Next item.....you will need to perform a Hard Reset on the Time Capsule to get it back to its factory default settings so that it can be set up again to work correctly on your network with your current router.
Post back when you are ready to proceed.