Accidentally formatted a NTFS partition with ext3
 

I have accidentally formatted (an important) NTFS partition (/dev/sda1) with ext3 file system from Linux (mkfs.ext3 /dev/sda1).

Is there any hope of recovering my data back :cry: ?

You need to look for NTFS recovery tools. A Google search of "NTFS recovery" yields a lot of results, but personally I haven't used any.

Make sure you don't mount the partition, because ext3 might go on writing to it. Check your /etc/fstab and remove all references to /dev/sda1. Manually unmount it if it's currently mounted.