Hi,
You can try the following
Make sure you dont have a stuck keyboard key (it happens to the best of us!). Heres some general info. Regarding the IDE issues i have assumed that you have one hard disk and that it is the master device on the primary ID channel.
Ensure your mouse and keyboard are plugged in correctly and are in the correct ports.
Make sure that the IDE cable is connected from ID port 0 on the motherboard to the back of the hard disk and that:
The ends of the IDE cable are connected (not the middle connection).
That the jumper on the back of the hard disk is correctly seated and that it is setup to be the master device.
The harddisk has a power connection to it (known as a molex connection).
Also make sure that any other IDE devices (e.g. CD drive) are connected properly (you may have knocked something) and that your grapics card is seated ok too.
If you get really stuck, count the beeps and tell us the motherboard make/model since these beeps usually mean something

S