How can water purifier line and sprayer line work but the water stopped coming through the faucet.. completely - no hot or cold water at all coming through the main faucet?

HI Silver...

Remove the aerator at the end of the kitchen faucet spout and then run water without the aerator in place. If water flows then you'll want to clean the aerator and reinstall. If no water, you'll need to shut off the water from below the faucet and remove the cartridge or stem assembly and clear the lines/cartridge of debris sediment.

Let us know how you make out...

Mark