How do I restore my iMac with no backup after it was erased through iCloud find my iMac

Question

I removed my iMac from my device settings on my iCloud on accident. I had bought a new one for my office and moved this one to my home for my wife.
Well, I set it up for her, did the migration from her old computer to her new computer. Worked like a charm, we sold her old computer.
It's been about 6 months now. Our home computer has all of our pictures....  Time machine was not set up.
A Few days ago I was using her computer and needed a password from my notes. I went to the notes on the computer and noticed that they were not syncing because we hadn't logged this home computer into my iCloud
As soon as I logged in my icloud the screen went to a password request mode .. So I put in my password and the screen froze, then rebooted to install OS X,  time machine, disk utility....
Then I got an email saying that my iMac was found and all data was erased....
Apparently, I removed the wrong computer from my devices on iCloud. Thinking I was removing her old computer we sold, I removed this one..
Is everything lost?
All I care about is my pictures and I don't know what to do...
The back up I found I tried to restore  but it got complicated when it told me I had to do a list of different steps bc the backup ..
I don't want to do anything and possibly ruin a hidden back up somewhere.
Called apple they said they didn't know why it what happened and said I had to reinstall.
I tried reinstalling twice and it won't even reinstall now..
I come home late from work and had no desire to get on the phone for hours so I came here..
Help
I don't even know why it was erased

Answer 1

Regardless of why it happened, the fact is that you have tried repeatedly to write data to the drive. This will result in overwriting whatever data were on the drive making any sort of recovery impossible. But you can give it a try:
General File Recovery
If you stop using the drive it's possible to recover deleted files that have not been overwritten by using recovery software such as Data Rescue II, File Salvage or TechTool Pro.  Each of the preceding come on bootable CDs to enable usage without risk of writing more data to the hard drive.  Two free alternatives are Disk Drill and TestDisk.  Look for them and demos at MacUpdate or CNET Downloads. Recovery software usually provide trial versions that enable you to determine if the software would help before actually paying for it. Beyond this or if the drive has completely failed, then you would need to send the drive to a recovery service which is very expensive.
The longer the hard drive remains in use and data are written to it, the greater the risk your deleted files will be overwritten.
Also visit The XLab FAQs and read the FAQ on Data Recovery.
Beyond this would be erasing the startup volume and reinstalling OS X:
Install or Reinstall Lion/Mountain Lion from Scratch
Be sure you backup your files to an external drive or second internal drive because the following procedure will remove everything from the hard drive.
Boot to the Recovery HD:
Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.
Erase the hard drive:
  1. Select Disk Utility from the main menu and click on the Continue button.
  2. After DU loads select your startup volume (usually Macintosh HD) from the
      left side list. Click on the Erase tab in the DU main window.
  3. Set the format type to Mac OS Extended (Journaled.) Optionally, click on
        the Security button and set the Zero Data option to one-pass. Click on
      the Erase button and wait until the process has completed.
  4. Quit DU and return to the main menu.
Reinstall Lion/Mountain Lion: Select Reinstall Lion/Mountain Lion and click on the Install button.
Note: You will need an active Internet connection. I suggest using Ethernet if possible
            because it is three times faster than wireless.