Inspiron G5 SE 5505, SA backed up files, restore failed

My Inspiron G5 SE 5505 wasn't booting to Windows properly. I used SA (SupportAssist) to create backup before resetting laptop. Restore failed and I now have a hard drive with .MIG files.

So I accessed SA from the boot options and selected reset my laptop by downloading Windows updates. I backed up my data to my 1TB hard disk and it downloaded and installed Windows updates. However, after doing so it started to restore from my hard disk and that failed, and after the laptop restarted it just didn't go to the restore part at all ! It just said Windows hasn't been installed correctly. 

So I reset my laptop once more, and couldn't restore then either. Now I have a hard drive with .MIG files I have no idea what to do with. The data is quite important and even if I could get a tool to extract it it would be a huge help! I tried the SA OS Recovery app but it doesn't detect my backup hard disk either! 

Could anyone help me?