Ubuntu 16.04 cannot detect wifi

Question

My PC cannot detect wifi. This is the output for sudo lshw -class network

seng@wseng:~$ sudo lshw -class network
  *-network UNCLAIMED     
       description: Network controller
       product: BCM43142 802.11b/g/n
       vendor: Broadcom Corporation
       physical id: 0
       bus info: pci@0000:06:00.0
       version: 01
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list
       configuration: latency=0
       resources: memory:f7200000-f7207fff
  *-network
       description: Ethernet interface
       product: RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller
       vendor: Realtek Semiconductor Co., Ltd.
       physical id: 0
       bus info: pci@0000:07:00.0
       logical name: enp7s0
       version: 07
       serial: 74:e6:e2:39:02:7c
       size: 100Mbit/s
       capacity: 100Mbit/s
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl8106e-1_0.0.1 06/29/12 ip=192.168.1.9 latency=0 link=yes multicast=yes port=MII speed=100Mbit/s
       resources: irq:47 ioport:e000(size=256) memory:f7100000-f7100fff memory:f2100000-f2103fff

Do let me know if you need any further information.

This is the output for command inxi -FX

seng@wseng:~$ inxi -Fx
System:    Host: wseng Kernel: 4.13.0-26-generic x86_64 (64 bit gcc: 5.4.0)
           Desktop: Unity 7.4.0 (Gtk 3.18.9-1ubuntu3.3)
           Distro: Ubuntu 16.04 xenial
Machine:   System: Dell (portable) product: Inspiron 3543 v: A01
           Mobo: Dell model: 04XW3R v: A00 Bios: Dell v: A01 date: 11/04/2014
CPU:       Dual core Intel Core i5-5200U (-HT-MCP-) cache: 3072 KB
           flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 8779
           clock speeds: max: 2700 MHz 1: 2194 MHz 2: 2194 MHz 3: 2194 MHz
           4: 2194 MHz
Graphics:  Card-1: Intel Broadwell-U Integrated Graphics bus-ID: 00:02.0
           Card-2: NVIDIA GF117M [GeForce 610M/710M/810M/820M / GT 620M/625M/630M/720M]
           bus-ID: 08:00.0
           Display Server: X.Org 1.18.4 drivers: (unloaded: fbdev,vesa) FAILED: nouveau
           Resolution: [email protected]
           GLX Renderer: Mesa DRI Intel HD Graphics 5500 (Broadwell GT2)
           GLX Version: 3.0 Mesa 12.0.6 Direct Rendering: Yes
Audio:     Card-1 Intel Wildcat Point-LP High Definition Audio Controller
           driver: snd_hda_intel bus-ID: 00:1b.0
           Card-2 Intel Broadwell-U Audio Controller
           driver: snd_hda_intel bus-ID: 00:03.0
           Sound: Advanced Linux Sound Architecture v: k4.13.0-26-generic
Network:   Card-1: Broadcom BCM43142 802.11b/g/n bus-ID: 06:00.0
           IF: N/A state: N/A mac: N/A
           Card-2: Realtek RTL8101/2/6E PCI Express Fast/Gigabit Ethernet controller
           driver: r8169 v: 2.3LK-NAPI port: e000 bus-ID: 07:00.0
           IF: enp7s0 state: up speed: 100 Mbps duplex: full
           mac: 74:e6:e2:39:02:7c
Drives:    HDD Total Size: 500.1GB (27.1% used)
           ID-1: /dev/sda model: TOSHIBA_MQ01ABF0 size: 500.1GB temp: 38C
Partition: ID-1: / size: 448G used: 116G (28%) fs: ext4 dev: /dev/sda3
           ID-2: swap-1 size: 11.91GB used: 0.00GB (0%) fs: swap dev: /dev/sda2
RAID:      No RAID devices: /proc/mdstat, md_mod kernel module present
Sensors:   System Temperatures: cpu: 50.0C mobo: 27.8C
           Fan Speeds (in rpm): cpu: N/A
Info:      Processes: 242 Uptime: 1 day Memory: 3320.4/7889.2MB
           Init: systemd runlevel: 5 Gcc sys: 5.4.0
           Client: Shell (bash 4.3.481) inxi: 2.2.35 
seng@wseng:~$ 

And this is the output via /etc/network/interfaces which looks like

auto lo
iface lo inet loopback

auto eth0
iface lo inet dhcp

Solution

I managed to solve it by these two steps !

1) Remove bcmwl-kernel-source

sudo apt-get purge bcmwl-kernel-source

2) Re-install bcmwl-kernel-source .

sudo apt-get update
sudo apt-get install bcmwl-kernel-source

Comments

[Kamil Maciorowski]

What is the output of sudo iwconfig?

[John Joe]

@KamilMaciorowski enp7s0 no wireless extensions. lo no wireless extensions. virbr0 no wireless extensions.

[Kamil Maciorowski]

In your research, did you see this? Installing Broadcom Wireless Drivers.

[John Joe]

@KamilMaciorowski no, but this post help. Thanks