Hello,
Your computer is trying to boot up using the internal LAN (network) port and/or is not finding a valid boot device when starting up.
Press F2 when you see the BIOS/Toshiba Boot Screen - You'll get to the BIOS (ussually blue/white/lightblue menus) go to the BOOT tab select the HDD and press F5 or F6 to move the HDD up to the number 1 boot option - Then press F10 to save - Answer YES and the system should reboot - If you get the same message "No Bootable Device" then your computer is no longer recognizing your Hard Drive as a bootable device.
If your hard drive has failed then you'll need to contact the "official support" for Toshiba - 1-800-457-7777.
Good Luck,
In Christ,
Trav...