Broadcom Limited BCM43142 (rev 01) driver installation on hp laptop with Ubuntu 16.04 LTS

Here's what worked form me

1.Turn off safe boot of your laptop (This is the biggest reason installation may not work. In fact was the reason in my case also).

2.Open terminal and type the following commands- 

sudo apt update 

sudo apt install firmware-b43-installer 
sudo apt install bcmwl-kernel-source

3.Reboot