It appears that a recent update from Microsoft for Windows 8 and 10 has messed up internet connectivity on a large number of computers. The problem is apparently in the area of DHCP, which is the process by which your router and/or your internet service provider automatically allocates an IP address to your computer. Without an IP address, you can't get online.
If you are having trouble connecting to the internet from your PC, or your connection keeps dropping, begin by restarting your computer. If that doesn't help, check out some other helpful tips on Microsoft's web site at https://support.microsoft.com/en-gb/help/10741/windows-10-fix-network-co... for more assistance.
Once you get back online, try to keep your computer connected for a day or 2, so that any future fixes issued by Microsoft get downloaded and applied automatically.