Hey Guys

So my XPS 15 was working perfectly fine one day to completly crashed the next day. (basically today)

When i booted, I get the Dell logo as per usual and afterwards it gives me a black screen saying i should repair my windows with an external drive and an option to go to UEFI boot settings.

So i got a bootable drive with the Dell OS recovery tool on it. 
It booted up the tool quite smoothly. I did some tests. Luckely no hardware fails. But my software was apparently all messed up:

Partition table - fail
boot configuration - fail 
windows health - fail

So no software repair possible.

So then I thought i should do a full system reset. 
In the tool there is an option to backup files before you reset.
When i start the sequence and it gives me the outcome, it hasn't found anything. Even on my desktop. 

0 bytes found in any of my directories and no option to do a backup.

So my questions:
1.How is this possible that my systems crashed so drastically in the first place?
2. Is it really that bad that all of my data is just gone or is there still some hope i can salvage some data? (maybe in another way?)

Thanks in advance for your insights