My router won't connect to the internet anymore

For some reason, my router wasn't on wireless anymore and I couldn't see the network on my phone, so I went on router login and did a factory reset and the network was visible back on my phone but I accidentally added my old device as a new one so it won't connect to the internet now and it says it can't locate IP address. Does anyone know how to fix this? I also tried doing the reset on the router itself and it didn't work.