I have a Desktop, using windows 8. Unfortunetly i was format my pc. Now i need my lost data. please help me.?

You should have backed up your data to an external source before formatting. it is now lost.

You're out of luck. If you lost data, you need to rethink your data backup strategy.

Unformatting.

If you didn't save your data to some storage device

then your data is gone. When you format it removes

all your data.

its not possible generally

but try a program named recuva.