Looks like you installed Ubuntu on the same partition where the Windows was. It is means, that the partition with Windows was formatted, and another OS was installed there. Part of your data was overwritten with data of newly installed system.
Here still could be a way to recover part of your data, but it depends on what kind of a data you're seeking for. You may try Dragon UnPACKer(I am not sure if it works on GNU/Linux despite the fact that this is Open Source, probably you need to launch it with WINE). It could recover some data like images(i.e. photo) and video, but I don't think that it can find something like Office documents.
What you have to do: load Ubuntu with live disk, next install there WINE(enter the
sudo apt-get install wine in terminal), download and launch the Dragon UnPACKer, open this program with root rights(enter in terminal to the directory where the program is, and launch it with
gksudo wine <paste_here_a_progam_name>). Next choose the plugin "Hyper Ripper"(or something like this, don't remember exactly, but you won't miss), you will see a menu that is asked for which format of files you wanna seek. (Un)check the ones in which you're interested, and open with this plugin your drive that most probably is the file
Beware that this is will take many hours; depending on a speed and size of your drive you could wait even whole day. As a a good side this program can find even some partially screwed files -- I have tried this with a dump of some screwed flash card in which a man asked me to recovery photos, and this found even partially overwritten ones.