I've not seen this little mishap before so we'll have to work through options to recover.
If you have an external drive you can install OS X using the Recovery Drive on the external drive. While booted from the external drive you should be able to see your internal drive files.
It might be possible to move it back from Applications (Launch Pad is a view of your Applications folder), but I suspect this will fail. You will be able to recover your files to the new OS X on external drive. Once your data is safely copied over, wipe the internal drive and clone the new install to the internal drive.
Open Disk Utility in Applications/Utilities.
Does Disk Utility see the drive? In order to reinstall OS X, you have to be able to see the drive in Disk Utility.
Options to try...
Hold down the Option key and restart. This should bring up a list of drives. If you see the Macintosh HD (default name) hold down the Shift key and select the drive. This would boot you in Safe Boot mode.
Another option would be to try resetting PRAM
1. Shut down your Mac. 2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4. 3. Turn on the computer. 4. Press and hold the Command-Option-P-R keys before the gray screen appears. 5. Hold the keys down until the computer restarts and you hear the startup sound for the second time. 6. Release the keys.