How to recover from accidently diskpart'ing an OS X drive, destroying everything?
If you can connect to a standard wireless WPA/WPA2 network, it should be possible to reinstall OS X from an internet connection. Try booting with 
⌘-Option-R held down as soon as you power on. Do not let go until the Apple logo is visible on screen.

Per this Apple support article:


  Newer Macs include the ability to start up directly from an Internet-based version OS X Recovery. Your Mac automatically uses this feature when the Recovery System on the startup drive isn't available. For example, if your startup drive encounters an issue, or if your startup drive has been replaced or erased. Internet Recovery lets you start your Mac directly from Apple's servers.


I would not attempt to do this until you have exhausted any options you wish to take for data recovery.