It sounds like she was injured, or there’s a mass or something in her head. Bring your rabbit to a vet ASAP. In the meantime:
* PAY ATTENTION TO YOUR RABBIT’S BEHAVIOUR so you can tell your vet the important information they need to know: Is she eating like normal? Drinking water like normal? Peeing and pooping like normal? Are her energy levels normal, and her mood, or is she listless and withdrawn? Keep a chart of her temperature, if you can. (Do not take her temperature if you have no experience doing this.) Is she grinding her teeth in pain (an irregular, crunchy, loud sound)? Is your rabbit breathing through her mouth (a very bad sign which might confirm your suspicion that her nose is blocked up).
* When rabbits feel unwell (for any reason), they often stop eating. When rabbits stop eating (for any reason), they go into ileus (a.k.a. GI Stasis), a painful and deadly condition. DO EVERYTHING YOU CAN TO PREVENT ILEUS. If your rabbit’s appetite goes down, encourage her to keep eating. Try offering her favourite greens. Carrot greens and dandelion are very popular; also herbs (which have strong smells), like dill, cilantro, basil, mint. Papaya and pineapple are also popular because they have digestive enzymes in them, but don’t go overboard because they’re high in sugar, and too much sugar can itself cause ileus. Try feeding her by hand, and speak in an encouraging tone. If she stops eating, force-feed her with a feeding syringe (a syringe with no needle) – mix her pellets with a bit of warm water to make a mush. If she really resists it, mix the pellet-mush with carrot baby food (plain, strained carrot) or canned pumpkin (pure, no added sweetener). If she stops drinking water, encourage her to drink by adding a tiny amount of apple juice to her water. (Pure, 100% apple juice with no pulp – not cider. Or you could try pineapple juice. You can put in as much as 1 part juice to 6 parts water.) If that doesn’t work, force-feed her Pedialyte. Whenever you force-feed anything, ALWAYS aim for the cheek, otherwise you might shoot the stuff into her lungs and kill her. Give her firm (but gentle! don’t force her if she struggles) stomach rubs, in the event she has gas (which can arise from disruptions in the diet, and which itself can cause ileus) – you can break up the gas bubbles with your fingers and push them down the digestive tract to the anus.
* KEEP HER COMFORTABLE. I may be wrong, but I’m willing to bet she’s not comfortable in a small cage alone in the basement. She should be somewhere she has room to stretch out and stand up; somewhere to hide when she wants to feel alone, and somewhere to socialize when she wants to be comforted. But, if the cage is the only possibility for now, at least bring it upstairs where she can be warm and nearby, and give her blankets (or, if she eats blankets, plain cardboard is fine – something more comfy than wire/metal/plastic). Frankly, I think you should sleep beside her and basically stay with her as much as you can. Speak in soothing tones.
* CONSULT AN EXPERT BY PHONE. If your vet’s closed, there still may be someone there to talk to you. Or perhaps another vet is open, maybe one in the next town over – call them, and ask for their advice.
Good luck, I really hope your rabbit pulls through.