How to recover lost partition and files after installation of Ubuntu on Windows partition?

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http://askubuntu.com – I have got a laptop from one my friend which has installed Ubuntu by choosing a wrong option and has re-partitioned the entire hard drive and has lost all his private files. I booted the laptop by a live Linux CD and I can see 4 partitions. First, one system partition 1,86 GB NTFS, then 2 X 46.5GB for Ubuntu and lastly a 603GB unallocated partition. He doesn't need to keep Ubuntu just wants to back his files as there are crucial. I know some parts of data have been overwritten but wondering if there is a way that I can recover the data? (HowTos)