If you added a disk or made any hardware changes, I would carefully check
the connection of the ribbon cables, the power cables and the jumper
settings on the harddrives and any other devices that is connected to the
IDE cables.

Furthermore, check bios to verify that the onboard IDE ports are enabled.

Unless you've formatted, try simply eiting startup help
file, remove floppy, hardboot, hold down cntl key unil
indows flag shows,  Best of luck.