1999 Honda Accord D4 light not working

Hi,

I own a 99 accord lx v4 and last afternoon the D4 indicatior light on my dask stopped working. The other lights- P, R, N, D3, 1, 2 work fine. I drove the car 20 miles back and forth yesterday and today. Is this a matter of a blown light or something serious. If it is a blown light would you have any instructions on how I could change it on my car.

Thanks so much,
Hanif