Complete Internet Repair is a portable troubleshooting tool that can fix many common Windows networking and internet-related issues in a click or two.
If IE is misbehaving, say, then checking the "Repair Internet Explorer" option and clicking "Go!" will re-register all the DLLs and OCX files that the browser requires.
A "Reset Windows Firewall Configuration" option will restore the Windows firewall to its default state.
And there are other options to repair Windows update, reset TCP/IP and Winsock, repair your SSL/ HTTPS settings, and more.
You need to use these with care, as some may cause more problems than they solve. Choosing to "Repair Winsock", say, might fix a broken internet connection, but only by restoring default Windows settings, which may also break other internet or network-related programs that you've installed (you'll need to reinstall these to get them working again).
If your Internet or network connection is broken then it may still be worth trying the program, then, but we'd recommend you use one repair option at a time. And create a System Restore point before you start, so you can easily undo Complete Internet Repair's fixes, if necessary.