Accidentally deleted Ubuntu system partition during attempted Windows installation [duplicate]
OK, so one good thing is you stopped the install. You can now do two things: 1>Get another computer with Windows installed and connect your hard drive to it. Then go to http://www.active-undelete.com/ and try using their soft. I'm not sure it will support ext3 or ext4 type partitions but it is worth a try...
OR
2> Burn yourself a live cd/usb of http://ubuntu-rescue-remix.org and see if it works for you.
Also checkout the https://help.ubuntu.com/community/DataRecovery page. Hope the links were helpful. Tell me in comment if any of them worked.