No bootable device found.. no boot sequence options

hello everyone,

i have a dell latitude 5400 laptop. my sister gave it to me so i can use it for my online schooling that started because of the virus.. she had all her files on it so instead of deleting everything manually i just reset the whole laptop. i went to setup in the startup... i chose to “WIPE OUT” and the computer rebooted....

i think i deleted everything.. like even logging in doesn’t come up!!

all that comes up is “no bootable device found.....press f1 for retry, f2 to reboot into setup, and f5 for onboard diagnostics”....

can someone please help me?? I don’t know what to do... i tried googling but the answers say stuff like “change boot sequence to LEGACY”

but when i go to boot sequence there’s no such options as legacy or UFEI..

i asked my sister for any hard drive or discs or anything to use to help set it up but she doesn’t know either!

i don’t know anything about computers and there are no repair stores open because of the corona virus 

can someone please help me??? or did i break the computer for good? i hope not..

but i’m a quick learner and if i can somehow fix this on my own i’m ready to follow the steps.. please just help me!!!