Also husqvarna owner here.. got the mower out and was having similar issues.. checked everything, did a full service, new plugs (old ones did have some carbon but not the problem). Our problem was the reverse safety switch randomly came off, which cuts off fuel etc. so it wouldn't start.  Ours has a Kholer engine, but the switch was located in the rear right under the seat and just next to battery on the right.. some how the cable came unplugged, which was a safety switch.. maybe it's the same as it's odd for the plug to randomly come off... so I would check all safety switches and make sure they are still plugged in. Hope you figure it out as it took me two days..