Did you remember to Save bios settings??
For most laptops, lan has to be after hdd, otherwise the hdd won't boot.
In older bioses, e.g., made before 2000 or so, you only have specific lists of choices to choose from.
In most more recent bioses, you can change the things listed in the bios's boot order to any order you want.
I have no idea how old your laptop is.
Find the specific model "number" that's on a label on the outside of the case.
Tell us what it is.
Were you trying to boot from a CD or DVD?
If you weren't, do you have a disk in a CD or DVD drive?
If you do, remove it!