What shall I do my dogs terrified of my lounge and refuses to go near it and will hide away in my garden but I don't know what he's scared of.how can I build his confidence
If your dog is small enough, you could just pick him up and then sit on the lounge to show him that it's not dangerous.

If he's a bigger dog, then treats may work. Coax him out of the garden with a treat and gradually work your way closer to the lounge. Once you get close enough, then sit on the lounge to give him treats, and eventually put a treat directly on the lounge for him to take.

Be patient, and don't try to coerce or push your dog. This process could take a few days.