MIDI Keyboard not recognized

I have a Dimension 3000 with Windows XP, a Yamaha keyboard, and Sibelius music writing program. All of these three worked great together before my hard drive crashed. Now with a new hard drive, I've reinstalled the sound car and the music program. However, the keyboard isn't recognized by the program (or my computer I'm assuming). I use the midi in and midi out plugs on the keyboard to a midi port on the sound card. Is there something I need to do so that my computer knows to look for a midi device at the midi plug? All I can think to do is click "Find New Devices" in Sibelius which results in nothing and look at the driver in the Control Panel which shows the MIDI plug active. *Update* For a couple moments, the midi out was working, but not the midi in. I could click "test" on Sibelius and it would play a scale on my keyboard. However, now the keyboard isn't listed as a device again and I don't know what I did to cause that.