WEP Encryption Key Changed - DNS Cannot Communicate With Resource Error

So after the change of the WEP encryption key, there is another issue that emerged out of nowhere again. This time it's the DNS server error, and other windows in our house can connect except for me. I can enter the security key this time however the wireless icon indicates a exclamation mark icon overlapping it. I tried using cmd and typed ipconfig /flushdns, ipconfig /release and ipconfig /renew with a reboot afterwards, changed the Internet Protocol Version 4 and 6 on their DNS server address settings, resetting the router and configuring the network adapter but it doesn't work.

Although, the windows 7 can sense the internet and connect it but the result came up "DNS server error" and "DNS cannot communicate with the resource error". I currently don't hold the real password for the router, however I managed to retrieved the old WEP password for the router. My cousin has the password, whenever he types the password now which I don't know at this stage doesn't work (Security Key Mismatch) and when I secretly tried the old password, it worked but with an exclamation mark on the wireless icon.