Well, if you "deleted" (erased?) the drive, and you have no backup, the data is gone. I don't think you're getting any of it back.
Try this (do exactly as described):
1. Power down, all the way off
2. Press the power-on button
3. IMMEDIATELY hold down:
Command-shift-option-R
You will need your wifi password.
This should boot to a special version of Internet Recovery from which you can install Sierra again.
You should get to "internet utilities".
It will take some time to load, so be patient.
Do you get there?
If so, open the OS installer and start "clicking through".
Does it let you install the OS?
The Mac will reboot one or more times, and the screen may go dark for a few minutes and then come alive again.
BE PATIENT.
Try this and see if it gets you going again.