sometimes the no-internet problem could be a:
- spyware problem (do you have an Internet Security Suite installed or something like McAfee Total Protection or Norton 360 that includes spyware protection with shields?)
- networking issue
- you haven't run the Network Setup Wizard for the first time yet to set up your network. start, Help, type in Network Setup Wizard, and dig for it. it's probably in overview. this only needs to be run once.
- you need to right click on your network connection and pick repair. this often fixes the problem. with wireless connections, this needs to be done often.
- tcp/ip settings (are you using DHCP - obtain address automatically? most configurations use DHCP)
- is the windows firewall causing a problem? (you really should be using an Internet Security Suite that includes a software firewall - there are sites that can down the windows firewall)
- problem with connection to modem
- a cable is unplugged. There should be an ethernet cable between the modem and the router's internet jack, and a cable between the router's port 1-4(one of them) to your computer (at least until you have set up all your wireless connections). OR just a cable between your modem and your computer. There should be for DSL a specially supplied phone cable between the phone jack on the wall and the modem, or for Cable there should be a CATV cable between the modem and the wall jack. Some people don't use ethernet cable, they use a USB cable between the modem and the computer, but I don't recommend this because it really slows down your computer.
- modem and router need to be "reset" (see below)
- modem gone bad (does it light up and blink when you are using it, like when downloading Vista SP1? some like belkin don't blink)
- router gone bad (does it light up and blink when you are using it during a long download, like downloading Vista SP1? some like belkin don't blink)
- gummed up Internet Explorer: wrong ActiveX controls installed or mangled due to spyware (solution: try a fresh copy of firefox and an anti-spyware package)
I have seen modems go gunnybags lately. and with the newer motorola surfboard cable modems comcast uses, sometimes the modem and the router need to be reset (in their proper sequence of course). If the Cable tech tells you that the modem is resetting itself, it's time for a new modem or a checkup on your wiring. splitters with one end unused can do this too (can be inside a wall - your Cable company probably doesn't keep track of whether there's a splitter in your wall casing the trouble). A tech visit will cost you. if your IE is gummed up, try using firefox.
if the spyware damage has replaced your desktop, I suggest reinstalling windows. you did keep your Windows 9x/ME/2000/XP/Vista CD/DVD didn't you? On some prebuilt systems like Dell's and eMachines it will be labelled "System Restore cd".
to "reset" your modem and router (no reset buttons please),
- unplug both modem and router. if there are VOIP devices plugged into the router, unplug them too.
- wait 10 seconds.
- plug in the modem and wait for the online light to go steady green. (if power light never goes on you have a dead modem - but you have to wait a few minutes for it)
- plug in the router. wait for the internet light to blink.
- plug in the VOIP devices.
by plug in and unplug I mean the power plug or wall adapter.