You are pretty much in a terrible situation, how valuable is it to get the data back?

When you delete a partition / format a disk, all the data that was present doesnt disappear, it just becomes in inaccessible unless it has been physically over written with data.

So if your Ubuntu installation has not overwritten the same disk location containing an important document then it is possible to recover that document using programs such as photorec which use data carving techniques to recover files.

However this is a long process and can only be achieved using a separate system.

And the real bummer is if all your original content (the files you wish to recover) has been over written with new data then you wont be able to recover it.

I think you should start re-writing your thesis.