Critical error message. No bootable devices found

If you require assistance, you'll need to be far more specific.

What is the exact "critical" error message you're seeing?  If it came with a numeric code such as 2000-0142, etc. post that.

What model system is this (i.e, Inspiron N5110, 7779,etc.).

What OS is on the system?

Do you have a current backup of your data files?

Thank you for your help. The critical error message "no bootable devices found" was all that appeared on the screen when trying to boot. Its a Dell inspiron 7790 AIO system bios 1.6.4. . Version build 4400.08.  UEFI Rom. On the pre boot performance check scan it comes up with code 4400.08 success. Hardware scan complete with no issues. No bootable devices were found. Possible causes could be a corrupt OS image or a boot device is not enabled in BIOS setup. If I press F12 when booting it comes up with UEFI; secure boot on, PTT is on. If I try the recommended fix in the BIOS boot sequence there is nothing in the boot option list do I cannot add or delete a boot or swap between options as most fixes say. I would really appreciate some help as I depend on the computer to case manage my mother with Altzeimers. Thank you. I have my files backed up on one drive. 

Hi!

Thanks for reaching out to us.

I’m Deepti from the Dell Social Media team. I understand that you're facing an issue with the system not booting. Please be assured that I will look into this and help you with the best available options to have this resolved for you at the earliest.

I have replied via private note.

-Deepti

I am waiting for your message via private note.

Please delete the system tag and your persona detail from public post due to security reasons and reply to my private note.

Thanks very much. If you need to contact me any other way my  and my

. Thanks 

Hiw do I message via private note? 

You can go to your Profile Page and check the Private Message icon/tab there.

You can click on the Private Message to open it and you can reply to it.

check your private messages again. We have sent the next steps .

I am sorry I cannot see how to private message. I have attached 2 photos of the screenshot for the first video link and I have reset as per the second video but without success

Are there some more stages I can follow to try and get my computer working? Thank you

Thank you Deepit. Can I start again first thing tomorrow as its nearly midnight in France. Thank you

I have attached another photo to my album. I cannot complete these steps as there is nothing under boot list and as file system not found I cannot add a boot oath manually. I have untenable and followed the rest of the steps although after the first action in the video all the stages are followed but there is not a yes after this? Can I not see the private messages as not available on my phone?