Inspiron 7720 - boot only to the bios setup

Hello all. After manipulations with efibootmgr my laptop can't boot from amy drives, only into bios setup. Last change - boot order. The first boot candidtate was selected as 0000, setup. And now I can't revert this change because my laptop boot only into bios setup.  When F12  key pressed i6n boot process, 'F12 Boot Options' label in bottom right conned is highlighted, but boot into bios setup instead. How to restore bot manager on my Dell Inspiron 7720?  Did I have any chanse to resolve my problem? Thank you wery much for any helpful advice.