It could be a hard drive problem or the MBR is corrupt or missing. This site should help. Also check your BIOS to make sure that Windows Boot Manager is the first option in the boot menu. To access the BIOS restart the system and at the Dell splash screen start tapping F2. While you are in the BIOS check to see that the hard drive is detected.

UPDATE:

Made a bootable USB and was able to boot up to my desktop. Everything seems to be there.

Rebooted without the USB and got a message saying no bootable drive could be found.

Rebooted with USB and instead of my desktop, it went to an install/repair screen.

I selected repair and instantly got a message saying my computer could not be repaired.

What's next? Install?

Tried fixing the MBR:

bootrec /RebuildBCD

Successfully scanned Windows installations: 1

[c:\Windows]

Add installation to boot list? Yes(Y)/No(N)/All(A): Y

The requested system device could not be found

bootrec /fixMbr

The operation completed successfully

bootrec /fixboot

Access is deined

I'd suggest resetting BIOS to defaults to see if it will make any difference. You could do this step by following instructions in the link below:

How to restore the BIOS (System Setup) defaults on a Dell Product

https://www.dell.com/support/article/us/en/19/sln245206/how-to-restore-the-bios-system-setup-defaults-on-a-dell-product?lang=en

If resetting BIOS to defaults doesn't fix boot issue, check out getro's possible solution in link below, hopefully it will be a help to you.

Dell Inspiron 13 No bootable device found

https://www.dell.com/community/Laptops-General-Read-Only/Dell-Inspiron-13-No-bootable-device-found/m-p/5140389  

LSUFAN:

Neither totally worked.

Regarding greto's suggestion, I don't have the same boot options under UEFI. I have Windows Boot Manager and UEFI: SanDisk, Partion 1 (neither of which work).

I can get to a login screen now, but it won't accept my password. I did the first time I started up on a USB (the only time it took me to my desktop.