This is due to a cold virus, as to were your mucus is trapped at the top of your nasal cavity, blowing your nose will produce a difference if the mucus is low into your nose. Blowing your nose when the mucus is at the highest of the nasal cavity will just release oxygen. Breathing a steamy hot substance will vaporize the mucus in the nasal cavity causing it to liquify and release. Then you will be able to blow your nose. Also try vapor rub on around your nose which will also vaporize the mucus in your nasal cavity.