Why won't a computer get internet?

So I went to a friend's house to fix their computer, it was really slow. After I did that, they told me they wanted to delete the password on their wifi because they did not even know what it was. They receive internet on their desktop by hooking it up directly to the modem. I entered in the default IP address, (the 192. something one) and rummaged through their wifi settings. It was westtell and I was not familiar with it but did see a tab that read Public LAN Settings. I checked Public LAN thinking it would make the wifi public, (closest thing I could see to deleting a password) and when the modem reset, I could not receive internet. The wifi still showed up but it asked me to enter in the password, which neither of us knew. What went wrong and how can this problem be resolved? Thanks.