The spray wand has a short plastic tube that the rubber hose slides over. Here's what it should look like, if it's not broken:
A 'band clamp' goes over the rubber hose to tighten it onto that little tube. If the band clamp is missing, you can get one at a hardware store - just find the size that fits over the rubber hose. If the rubber hose end is torn or cracked, just make a new clean cut with a knife.
But if the plastic tube has broken off the wand, you need to get a new wand. Good news - it's not expensive.
This one's only 8 bucks.
Hope that helps you, if so please rate my solution, thanks and good luck!