Do not puncture the can in any way as I will explode in your face. If you cannot replace the nozzle then discard it. Sometimes the can of starch will stop spraying after a while so I do the same thing I do to other paint sprays, I turn it upside down and spray a little to clear the nozzle and have had less problems with waste.
Buy a new can of the same brand starch Borrow the nozzle from the new can until the old can is empty. Then put it back on the new can and move on!
If it’s not too old or you still have the receipt, take the broken one back and exchange it for a new one. Most stores like Walmart or national chain stores will do an exchange with no receipt for a small item like that!