When you installe Linux on the Windows drive... Did you do any type of partition resizing, splitting, whatever? Reason I ask is that if you did your windows partition could still be there. have you checke your /etc/fstab to see what partitions are mountable.
Of course, if you did use the whole drive for Linux, it would be very difficult to recover any data. I have heard of recovering from partitioning and formating but usually that is before any data has been written to them.