[SOLVED] No bootable devices found

[Aelidyia]

After trying to get rid of a nasty Bitlocker on a Dell Latitude 5580 Laptop (I formatted the C: disk through the command prompt)
I am now in front of a black screen saying "No bootable devices found. Press F1key to retry boot, F2 for setup Utility F5 to run onboard diagnostics.

I checked in the system info and it says "Primary Hard Drive =(none)"
I think this is the issue, but how do I solve this ?
when I use the onboard diagnostics option it doesn't find any errors.

 

[rgd1101]

if you format c drive, there is on os.
reinstall the os

 

[Aelidyia]

if you format c drive, there is on os.
reinstall the os

Thanks for your answer, but how do I do that if I can't get into windows

 

[rgd1101]

on a working pc. download windows installation media from MS website