I have tried to set up a wireless network in ubuntu 9.04, but always get error response. I give all the network information requested but still cannot connect. The router is set and working working alright. Even my laptop can recognize the router, but still cannot connect to the internet. I need help from anyone that can help me with a step by step procedure on how to resolve this problem. Thanks in advance.

Big problem,

1)Make sure you have the correct driver loaded for the wireless card you are using

2)Ensure that your wireless is actually turned on (Many laptops have a physical switch to turn the WLAN card on/off)

3)Make sure you are using the right utility for the WLAN configuration for instance probably using wpa_supplicant if you have a wpa encrypted WIFI

4)If you run a network scan can you see any networks?

5)If you remove all encryption from your network can you connect

6)Have you tried connecting using CLI tools only taking out the GUI components

Some questions:

What Distribution are you running?

What type of encryption are you running on your WIFI?

What are your using to try and connect to the wifi with?

Is this a Laptop or a Desktop with a WiFi card?

Can you connect to your LAN, but not to the Internet?
(If this is the case it may be routing issue)

I am using a built-in wireless card to connect to the internet. What I don't quite understand is that on the same computer when I switch to Windows(Microsoft), I get internet connection easily. Synaptic Package Manager seems to suggest that I have all I need to connect yet I am unable to do so. I am sure something is missing. I still need help in solving this problem.

Scheidel21,
Thanks for your help. My wirelss card is built-in.
I am running WEP on my WiFi.
I use a router.
It is a laptop with a WiFi.

I have no idea what you mean by CLI and GUI. Please continue to help.

CLI stands for command line interface. For example, you can run the Gnome Terminal program and then enter:
/sbin/ifconfig
This command will list all of your network interfaces. The wireless interface may have the name "wlan0".
If there is an IP address listed on the second line for wlan0, then you have an IP address.

GUI stands for Graphical User interface. Firefox is a GUI program. Where as `ping' is a cli program.

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It would be a good idea to check whether your wireless device is working, and can see Access Points (APs). If your connection tool was able to scan for APs and list them, that indicates that your device and device drivers work. The following program will scan for APs. It is provided by the wireless-tools package. You probably already have it installed, but if the command can't be found, then use your package manager to install it.

sudo /usr/sbin/iwlist <wireless device> scan

Your wireless device is most likely named "wlan0". If so then the command is:
sudo /usr/sbin/iwlist wlan0 scan

Report the results. If you don't see any APs, then we need to move backwards and see why the wireless device isn't working. If you do see APs working, we can look forward and look at the WEP configuration.

Also indicate if you use DHCP.