Hi D2,
Congrats on your new baby boy, you have come to the right place for help.
Firstly, your supply will definately NOT have dried up after just one day/night. However, if you are not feeding you must ensure that you express as if you don't this will over time have an effect on your supply and also could lead to blockages and Mastitis.
Please invest in a pair of Silverette they honestly will save your Breastfeeding relationship. Your nipples will be completely healed within 2 days and you will be pain free. They definately are a godsend to breastfeeding mothers
It does sound that you are completely blocked on the left side. Have you tried Hand expressing This really is the most effective way to express. It is better than all pumps. Before expressing apply a warn flannel to help the milk flow and have your baby near you so that you can see/hear and smell him.. this will help you let the milk flow.
Try feeding whilst you are on all fours (hands and knees!) this will let gravity help get the milk to flow.
Massage the breast down towards the nipple for a few minutes before trying to express.
You could gently use a wide toothed comb to comb the blockage down towards the nipple.
Hang in there, and keep trying AT LEAST every 2 hours to clear your blocked breast, otherwise it will only get worse. FEED FEED FEED FEED FEED and you will get thru this.