Drivers for Broadcom BCM43142 wireless card of Ubuntu/Debian 64-bit Linux
1.Check the wireless card type
lspci | grep -i net
2.deb URL
You can download this .deb by wired network or use the other PC then copy it into your laptop.
3.Linux shell
sudo apt-get update
sudo apt-get install linux-headers-generic build-essential dkms
sudo apt-get install linux-source
sudo apt-get install --reinstall bcmwl-kernel-source
sudo modprobe wl
sudo dpkg -i wireless-bcm43142-dkms_6.20.55.19-1_amd64.deb