Installing Realtek wifi driver in ubuntu (any version)

• First upgrade the kernel to 3.16 as shown in accepted answer at this link
• reboot into the new 3.16.x by command sudo reboot
• After rebooting, run sudo apt-get -f autoremove
• Now we have to remove old kernel, for that, first list the kernels currently present by command sudo dpkg --list | grep linux-image
• It gives a list of kernels, identify the older version, for example linux-image-3.11
• Give command sudo apt-get purge linux-image-3.14
• Now give command : sudo update-grub2
• Now reboot by sudo reboot
• Now we have to install realtek driver. For that follow below commands :
  1. sudo apt-get install linux-headers-generic build-essential git
  2. git clone https://github.com/lwfinger/rtlwifi_new
  3. cd rtlwifi_new
  4. make
  5. sudo make install
  6. sudo modprobe rtl8723be
• This rtl8723be in last command was the driver I required. There are many other drivers of realtek in rtlwifi_new. For me, rtl8723be was required, you may require some other driver. To check which driver you need, give command lsusb and search the output list for something like 0bda:b728 Realtek Semiconductor Corp. This b728 can be something else, and this will determine driver required. Google for more info.