Without an internet connection, you will need to download several packages on another computer and transfer them on a USB key or similar. Please go here and download the following: http://packages.ubuntu.com/
build-essential, libc6-dev, gcc, g++, make, dpkg-dev,
linux-headers-generic and linux-headers matching your running kernel.
Find out your running kernel with:
For example, if you get 3.5.0-19-generic, then you will need to download and install linux-headers-3.5.0-19-generic. When you have all these packages downloaded, move them to the desktop of the Ubuntu machine and install them with:
sudo dpkg -i Desktop/*.deb
The wildcard * means install all the .deb files. Be sure to download 32- or 64-bit as appropriate. At the download site, 32-bit are called i386 and 64-bit are amd64.
Now get the driver package here: http://dl.dropbox.com/u/57056576/DRIVERS/REALTEK/rtl_92ce_92se_92de_8723ae_linux_mac80211_0006.0514.2012.tar.gz
Transfer it to your desktop, too. Right-click the tar.gz and select Extract Here. Back in the terminal, do:
sudo make install
sudo modprobe rtl8723e
Let us know if you get stuck.