My computer fell

Usually, your computer tries to "boot" from multiple sources:

1. 3.5" diskette drive, if installed, functional, and a boot-diskette is inserted
2. CD-ROM drive, if installed, functional, and a boot-CD (such as the Windows XP CD-ROM) is inserted
3. disk-drive, if installed, functional, and the "boot" record can be read from the disk-drive
4. from the Ethernet network, via a "networked boot server"

So, "check cable" means that either no Ethernet cable is connected to the computer, or that the "networked boot server" is not installed, or the boot-server did not reply.

What this means is that your disk-drive was damaged by the fall, and the "boot" information cannot be read from the disk-drive.

So, you need to replace the disk-drive.