Cant boot my Acer Aspire one

Hello,
I have an Aspire one Acer with Intel UNDI, PXE-2.1(build 082)
Copyright 1997-2000 Intel corporation.
but every time i switch it on this is what comes up on the screen;
"Intel UNDI, PXE-2.1 (build 082)
copyright (C) 1997-2000 Intel corporation
For Realtek RTL 8101E/8102E PCI_E Ethernet controller v1.09 (080602)
PXE-E61: Media Test Failure, check cable
PXE-M0F: Exiting PXE ROM.
No Bootable Device-- insert boot disk and press any key".
What should i do?
my Email is; ***@***