My Lenovo Ideapad u165 wireless doesn't work

I'd rather comment but can't sorry!

which version of Ubuntu are you using? I encountered the same problem when I upgraded to Natty on my Lenovo Ideapad, also Broadcom 4313. You could try the solutions here: http://ubuntuforums.org/showthread.php?t=1700897

Ultimately I downgraded because nothing worked for me & everything is fine now. I'll wait for the next LTS. Hopefully you'll find a solution! I shifted my home to a separate partition so that I can do fresh installs without erasing my documents.

For my Lenovo U160 I blacklisted the acer_wmi module and afterwards the wireless worked perfectly. Maybe that solves it for you as well.

in

/etc/modprobe.d/blacklist.conf

add

blacklist acer_wmi