No sync means that your router is not synchronising with your local exchange, therefore you have no internet connection. This article will help you diagnose a no sync fault and a few simple ways to resolve the issue.
Do I have a No Sync fault?
The chances are you have already tried these, as they may seem a bit obvious. However, it doesn't hurt to double check. If you are unable to connect to the Internet, first, check to see if the router is plugged in, switched on and that all the cables are connected securely. Also if you are using a wireless connection connect your computer, or any other Device you may be using, to your router via an ethernet cable.
Then check your phone line, pick up your handset and see if you have a dial tone or experiencing any noise down the line. Any issues with your phone line will be causing issues with your broadband too. Before raising any broadband fault it is important that you raise any landline faults with your phone provider first.
If your phone line is working you now need to check your router/modem. Have a look for the DSL Light, this can also be referred to as the broadband light depending on the make/model of your router. If the DSL light is off or flashing then you may have a genuine no sync fault.
If you think there is a genuine fault on the line, you will need to perform a few simple tests first. This will rule out any possibility of your equipment or internal wiring causing any problems. Click on the following link for further diagnostics