Based on the information, you still seem to be able to see your wlan0
Since you can see wlan0 and it is "up", all that remains is to use your network management program to define the access point that you want to use.
Originally Posted by mayor89
I am not familiar with your wireless card or the distribution that you are using. Personally, I like to use wicd as my network manager for wireless connections because I can get it to do what I want it to do. I get frustrated with the GNOME wireless network manager, because it seems to frequently behave similar to the description of what you've given here.
Should your wireless firmware actually be missing or in conflict with something else (such as multiple drivers both attempting to communicate with the network card, that would also exhibit these kind of symptoms, so that's something to diagnose, but not necessarily the cause of your problem, just a factor to eliminate in your problem solving diagnosis.
Wireless Tools for Linux has some useful information. So does https://wiki.archlinux.org/index.php/Wireless_Setup and WiFi - Debian Wiki
These may either help directly, or at least point you to some other ideas and some diagnosis techniques. I've used them in the past when I've run into issues. Hope they help you too.