What year? That makes a huge difference.

There are some years (basically any Sentra pre-2000, I believe) that have only one dual-element bulb per headlight; if either the high or low beam goes out, you replace the entire bulb. And on the first-gen (‘82–86) it is even more fun.

Heh, Jerv is right it is a lot of fun on some models. Older mid-90s to early 2000s are almost always a simple pair of dual-beam H9004 bulbs, while the newer 2004–2010 models are the H9008 dual beam so if your high beam works but your low doesn’t or vice-versa you change the whole bulb just one per headlight assembly in both cases. It’s usually just a simple matter of pulling off the rubber boot on the back of the bulb assembly, twisting the socket counter-clockwise to release it’s tabs and pulling straight out. Then swap the bulb being careful not to touch the glass with your fingers and do it all again in reverse.

And by “careful not to touch the glass”, that means do not touch the glass with your bare fingers! I usually have latex gloves around the car and house anyways but even grabbing it with a paper towel works.

That only really applies to 900x-series bulbs though. If you have an older one that requires replacing the entire sealed beam assembly is a different matter.

I have had success with grabbing halogen bulbs with paper towels. If you use your bare fingers, skin oils with stick to the bulb and crack it when you turn it on.