Wireless network not working

Hi,
I am a new to Ubuntu linux and trying to learn it. I am using ubuntu 10.04. I am getting problem in setting my wireless network. I set it up properly and was working fine. But suddenly it stopped working, though the wireless icon saying that it is connected, but can't load any page. I tried many a things, but in vain.
Also I have few queries -

  1. How to check the type of wireless network card using.
  2. How to check from terminal whether wireless network working?
  3. How to check if the speaker is fine or not? In my system, the headphone is working but not the speaker.

Thanks in advance.

What do ifconfig and iwconfig show?

Can you ping anything? Your wireless router, for instance? ping -c 4 192.168.x.x where you should substitute your router's ip address for 192.168.x.x

How to check the type of wireless network
1.Go to the Start menu and open the Control Panel.
2.In the Control Panel, open the Device Manager.
3.Locate Network Adapters in the Device Manager list. Click on the plus sign next to Network Adapters to expand a list of all networking devices on your computer. Your wireless card should be listed, and most likely a LAN adapter as well.
4.Alternately, you can open the Network and Sharing Center in the Control Panel, and then click on "Manage Network Connections." Find your wireless connection in the list and right-click it, then select "Status." Under the Status menu, click "Details." This will produce a list of information about your Internet connection, including your wireless card.