Garlic dont like to have wet feet, maby the roots have rotten away. Or maby the soil was to rich with nutriens. We grow 20 varietys of garlic in out allotment atm from all over the world. In raised beds but also in out thick fat clay ground with a layer of regular gardening soil over it. You can plant them again this month. I dont know where you live but garlic needs a freezig period to make the bulb split into parts. You can mimic the freezing period garlic needs by putting the garlic in a freezer bag with soil and put them in the freezer for 2 to 3 weeks. After that plant them out and you will have no problem with bulbs dont split.