How to fix an acer aspire one D257- 1437 from not having a bootable device?

Hello,
so i have an acer aspire one D257-1437.
wheni turn on my laptop it appears the screen that says acer <press F2> & <press F12>
after that this is the information that comes out.

Intel UNDI, Pxe-2.1 (build 083)
copyright (C) 1997-2000 intel corporation
this product is covered by one or more of the following patents:
US5, 307, 459, US5, 434,872, US5, 732, 094, US5, 570, 884, US5,115,776,and US6,327,625
Realtek PCIe FE family controller series v1.24 (10/07/10)
PXE-E61: Media test failure, check cable
PXE-MOF: Exiting PXE ROM.
no bootable device -- insert boot disk and press any key

so i press any key and the same msg comes out.
so here is the problem i have no idea what is a boot disk, and my computer doesnt have a disk drive bcus is a small "notebook" computer.

i don't know what to do.
anybody help? please?