Assuming you're running Windows 10, the details are below.
To change the DNS settings on your Windows 10 device using Control Panel, do the following:
- Open Control Panel.
- Click on Network and Internet.
- Click on Network and Sharing Center.
- On the left pane, click on Change adapter settings.
- Right-click the network interface connected to the internet, and select Properties.
You then need to highlight Internet Protocol Version 4 (TCP/IPv4), then left click properties.
Then go to the second box and check 'Use the following DNS server addresses.
In the 2 DNS server boxes, put 8.8.8.8 in the first and 8.8.4.4 in the second.
Select OK, and it's probably better to restart your PC. Hopefully, it should then be OK.
Keep these instructions so you can go back to the default when it's all fixed ( hopefully!! )