Take a look at the network card. If it glows a led when a cable is connected? If not, then either there is a breakage in the cable, or the equipment to which it is connected, switched off or faulty.
In the case that the opposite end of the cable connected to the router located in your home, check off whether his somebody, or pulled out of him cable. Check the most of the network card and socket of the router. If the latter is faulty, move the cable to the next.
If the opposite end of the cable connected to the equipment located at the provider, call support and report the incident. Experts will find the break and fix it, or repair equipment. Any consultant will tell you that at the moment the equipment is prevention, and will tell you the approximate deadlines for its completion.
If you have just replaced the network card, and a new access to the Internet is missing, despite the fact that the led glows, maybe the fact that the provider keeps a record of MAC addresses. Let support new MAC address, and soon access will be resumed.
Led can glow, despite the lack of communication, and in that case, if the equipment to which the cable hung. If you are using DHCP, reboot the computer, then check whether he has received an IP address automatically. If not, either restart your home router, or, in his absence, report the problem to the provider. After resolving the problem, restart your computer again.
If the problem persists, check the router or gateway by using the ping command. It is possible that the equipment responds, but still I can't access any website. So, the fault is located on. See if your ADSL modem is connected to the telephone network. And if you have not ADSL, and LAN, check to load the website provider. If it is loaded, and the other sites - there may be also conducted prevention (find out about it on the phone), or you simply forgot to pay a subscription fee.
When accessing through GPRS/EDGE/3G, reconnection often occurs when forced to break the previous one. In Linux or Windows use, respectively, programmoj KPPP or regular software modem. Symbian use the included supplies this OS utility the "connection Manager".