My 2 yr old son pressed something on the phone. When I saw it, it was showing 'clearing device'. I tried to switch off the phone when it was showing that hoping that clearing the data would be stopped, but it didnt help. When the phone started up, all my data was missing..except installed applications. My data is very very important and I dont have any backup. Someone, pleeeeease help me how I can get my data back....

If you didnt make backup on regular basis, then your out of luck. Lessons learned, backupping important data should be standard behaviour.

I don't know about the N9/N950, but if you can mount it as usb mass storage, you might have some luck using some programs to recover data (Recuva comes in mind, but there are many).
If that is true, then avoid changing anything, adding any files or anything like that, because the more changes you do to the files, the less chances you have of recovering it all

Maybe you can flash ubiboot to it, hook the phone partitions to a linux computer, and run testdisk or photorec on them.

Edit: Aha, or if all your data is on MyDocs, then no need for ubiboot, mount it in mass storage mode and try if these programs can recover some data. But what's overwritten that's gone.