No bootable device after failed Windows 7 installation via Bootcamp

While trying to install Windows 7 via Bootcamp on my MBP Retina today I really messed up.

After getting into the drive selection in the Windows installation utility I deleted the other partitions (3 of them - as I remember one 60mb, one 200mb,) to get more space for my Bootcamp partition. After I deleted them (not formatted anything - just deleted) it just showed one huge unpartitioned disk with the whole ~250gb of my ssd. I realized that I messed up and exited the installation routine just to find out that I can't boot into anything right now.

When I do a regular restart it shows an error message "no bootable device - insert boot disk and press any key" - I also tried the "alt+cmd+r" method which doesn't do anything...

Please send my any ideas/tips how to go on - I have really important documents on that machine and I haven't made any backup.

UPDATE:

I tried to connect it to a second mac via thunderbolt/target disk mode and get the data with testdisk but i'm kind of stuck - when i connect it first it says something like "the medium couldn't be read" but I'm able to see the ssd via disk utility! But what medium should I select in Testdisk?