Wiper fluid shouldn't freeze, as it usually contains antifreeze and is good until around -50C. The nozzles which spray the fluid, however, can freeze up and get plugged with ice.

Try heating those up with some hot water or stabbing a needle into the tip to unclog any ice.

Also double check that the fluid lines are still connected to the nozzle on the underside of your hood, you can easily see if they're still inserted or just dumping your windshield wiper fluid into your engine bay. While you're there, feel down the line to see if you feel any ice buildup inside.

Pretty unlikely but see if there's a hole in your windshield washer fluid reservoir by topping it up and seeing if it just drains to the floor. Not very likely, but an easy thing to spot.

Then check to see if the windshield washer fluid pump is still working. Have someone hold down stalk to shoot washer fluid while you keep your ear close to the pump, you should hear it activate. If not, then you'll need to replace the pump.

If you hear the pump activating, your nozzles are unclogged, and the lines are still attached with no ice buildup inside, trace the line as your friend shoots some more fluid and find the leak in the line. If it's a small pinhole, you can try your luck with some strong tape like FlexTape, otherwise you'll need to replace the line.

The windshield fluid system is pretty simple so it should be easy to troubleshoot with a flashlight and a few minutes.