Please, help! – Can’t connect to WiFi

Hi all,
I recently started working with another Internet provider with two home laptops connected to the WiFi network. One of them is set up as the main computer of the network but eventually when its OS was reinstalled, we fail to connect at all. We can still see the network and it's at the top of the list but it doesn't accept the password. I have tried so many times that I feel I'm already not sure if I remember the password correctly. Please, tell me how to get to the settings and whether I need to change the password altogether. Thank you in advance.
