There are good chances to recover the whole previous partitions if you stop working on your hard disk drive IMMEDIATELY. The longer you use the hard disk, the more risk your data is exposed to.
I suggest you to take a look at this answer.
Aditionally, as suggested by @Private, run a search for "data recovery" in this site and I am sure you'll find a lot of useful answers.
In your case, and considering that you have already write a lot of clusters, you may experience some data loss (which may be a big amount of data). And maybe you'll be in need to first remove your current partitions (by formatting the whole disk NOT THE PARTITIONS but the disk itself) in order to recover the previous. These tasks can be done with a simple Ubuntu Live CD and installing the required tools (GParted, testdisk, etc.) or a GParted Live CD/USB
I hope you find a way to bring your data back with these information but if you need further support don't hesitate to drop a comment.