Lie down on your side with the clogged nostril higher than your clear nostril. Breathe normally and you'll notice your nostril will unclog after a few minutes, works 90% of the time.
Think of the clog as a mass behind your nose and gravity is shifting it to the middle. FYI it might switch to the other nostril, so it might take a few attempts before you clear both and at the very least you get a bit of easy relief without meds or more aggressive methods.
Supposedly it has nothing to do with gravity. It's a physiological reaction to pressure on your armpit. Supposedly you can induce it in any position. Put pressure on your right armpit and your left nostril will clear. I've never tried it.
Do not listen to medical advise on a public forum. Most advice will not help and some may actually be harmful.
Ask a doctor or at least pharmacist.
My current understanding (as an engineer not a medical person) is that the human body shrinks one nose side itentionally. This way you have a wide nose way and a narrow one. This leads to different airspeed which lets you smell different stuff better. The body changes sides in intervals. One allergic reaction is that the interior of the nose swells more. So the narrow path will become even narrower until it blocks.
There are substances that combat this swelling, but using them for too long can severely damage your sense of smell and health.
I have hypertrophy of the turbinate in the right nostril. It's blocked basically all the time. I was prescribed fluticasone and what's basically a salt water rinse. Neither really does much. I also have GERD, so I ordered an under-mattress bed wedge to see if the elevation can solve both problems at the same time.
I had issues with my nose for ages and got the tip to use a Rhino Horn from a friend. Using it daily helps a lot, but still one passage gets clogged up regularly. This is a cheap way to clear the passages, as all you need is water and kitchen salt. (later I discovered I have hay fever... ah well, this works better then any medication.
I use a version of this, it's based on the neti pot from india. Completely natural technique and does more than clearing our your sinus. It also stops any post nasal drip, Globus (lump in the throat) and can help with snoring.
Every situation is different so it is best to check with your doctor.
For me the surgery was quick, I didn't even feel any difference when I woke up from the anaesthesia. I was released from the hospital within the same day. I rested at home for a few days, had to avoid lifting heaving stuff or sports for a few weeks.
Now I can breathe without having to open my mouth all the time.
You have to get this from the pharmacist counter and show ID.
The government replaced pseudoephederine (how Sudafed got its name) with phenylephrine as the easy access decongestant. It has had multiple studies done that show it is about as effective as a placebo.
I don't know why this works or if it will work for you, but it works for me like 95% of the time when I have a mild cold or something. Breathe through your nose as slow as you possibly can. That's it. Obviously don't pass out so if you feel you have to, then take a few normal breaths. It helps if you're calm and your heart rate slows down.
I used to get addicted to nasal sprays all the time and haven't used one since I found this method.
Hold your ear on the blocked side about level with the ear canal and pull out wards, the place your opposite thumb on at the bone under your eye and next to your nose and push in the same direction. Should open things up.
Steaming hot shower, get your face warmed up, and try and blow your nose and clear it up as much as possible.
Grab a bowl of hot water with salt to make a saline solution (cool enough to dip your fingers in though) should be a bit saltier than tears but not more than that. Pour a bit into your hand and snort it in small amounts at a time, this may be hard at first but easier once you get the method down. You should start to taste the salt water in the back of your mouth. Do this a few times in each nostril, and finish off with fresh water if you can't stand the taste, but try let the saline in as much as possible. Towel dry, and give it a minute or two, then blow your nose. Repeat if necessary. After 10 Min your nose should clear right up as the salt will help break all the mucous up.
Do this periodically or seize the moment when your nose momentarily clears enough.