I just installed Ubuntu 13.04 onto my Dell inspiron 1545. I've tried almost everything on askubuntu with no luck. My wifi network is not being detected at all and I cannot manually add it. Please help!
Probably you need proprietary drivers for Broadcom. Try connecting through a cable and see if it works. I had the same problem with a Dell. I suggest the following: Try to see if the wireless card works when you load ubuntu with livecd. For a strange reason I could connect with the liveCD but not after the installation. My problem was solved when I connected my laptop with a cable and then downloaded the proprietary drivers. Try both the "additional drivers" program and installing the appropriate drivers and by installing the package using synaptic.
Here How to Install Broadcom Wireless Drivers you can find more details about how to install the Broadcom drivers
Note: The program "additional drivers" is called that way in ubuntu 12.04. Here http://linuxg.net/how-to-install-additional-drivers-in-ubuntu-13-04-from-the-gui/ you can find how to add additional drivers in Ubuntu 13.04
The trouble is with Network Manager I like to use WICD because it is a simple and easy to use network manager. Its a very good alternative to network manager in Ubuntu and it seems to always work when Network Manager doesn't. To install it just open up the terminal. Now download the latest NetworkManager, in case you need to reinstall it if WICD doesn't work
Then to install it
And now you need to uninstall NetworkManager:
Now you can find WICD in your menu Start WICD, find the network you want to use and enter the information needed, password, encryption, etcetera and choose Automatically Connect to this network. You should be good to go!
WICD may also be available in Ubuntu Update Manager so you can look there first but it is important to uninstall Network Manager completely to prevent conflicts!!