wireless - Wifi is enabled on 13.04 but cannot connect. on Dell Inspiron. Recommended solution does not work

I recently upgraded to Ubuntu 13.04 from Ubuntu 12.10. However, since then although my wireless network is detected, I cannot connect to it.

Ubuntu keeps on trying to reconnect with the network but is not successful. Same machine on Windows 8 I am able to connect to the same wireless network.

Also, Ethernet is working fine as I am able to connect to the same network through Ethernet on Ubuntu.

My lspci -nn output is

12:00.0 Network controller [0280]: Broadcom Corporation BCM4313 802.11b/g/n Wireless
LAN Controller [14e4:4727] (rev 01)
13:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd.               
RTL8101E/RTL8102E PCI Express Fast Ethernet controller [10ec:8136] (rev 02)

I already tried the solution in this post Broadcom Corp. BCM4313 Wirelss not detected in Ubuntu 12.10 but it not solving my problem. The situation is the same.

Please help me. I do not want to switch to using Windows again.