Checking the issue with these two commands to find out what Wi-Fi adapter you are using and do you have any information about missing firmware.
sudo update-initramfs -u
We need a temporary internet connection to fix WiFi. Ways to connect :
Connect USB cable and use USB Tethering in your phone to connect your computer to the internet (through phone's cellular data/WiFi)Use wired ethernet cable for connecting to internet.
You should install the corresponding header of your kernel. Open terminal and type:
This as first:
sudo apt-get install linux-headers-`uname -r`
Next, install the packages necessary for building :
This as second:
sudo apt-get install git build-essential dkms
Then type in terminal as third:
And then type this as fourth command in order, everything in one line.
git clone -b extended --single-branch https://github.com/lwfinger/rtlwifi_new.git
Type this as fifth command:
sudo dkms add rtlwifi_new
Type this as sixth command:
sudo dkms install rtlwifi-new/0.6
If you will have issue with typing commands one by one, use this one-liner:
sudo apt-get install linux-headers-`uname -r` && sudo apt-get install git build-essential dkms && cd && git clone -b extended --single-branch https://github.com/lwfinger/rtlwifi_new.git && sudo dkms add rtlwifi_new && sudo dkms install rtlwifi-new/0.6
And then restart laptop.
Other methods described here: