I need help with my Rabbit

Gerd I have raised rabbits, but I'm not sure I understand the problem. What do you mean by "has the ear very hard"? Has the ear dropped down to the side while the other ear is up? Can he hold his head up?

yes it has one ear dropped down and the other one is up, but yes, it can moves its head very well.

Are you sure he's sick? Lop eared rabbits often have one ear up and one ear down until they are fully grown, and sometimes permanently.

but the problem is that the ear dropped down is hard like a stone but the other one is normal (soft).

A very hard ear can indicate a a middle- or inner ear infection. An ear infection can causes the tissues of the ear and inside the skull to become inflamed and to fill with hard,( tough, cheeselike texture) pus. This infection can spread to the brain and cause what is called head tilt. I suggest you take your rabbit to a good vet, and since this is a problem that is caused by bacteia he can give you antibiotics to possibly solve the problem. It will not go away on its own. Good luck.

Thanks for your help I took my rabbit to a Vet, and he told me the rabbit had some Acarus in the ear, so he gave me some antibiotics

Glad to hear it worked out gerd. I've had rabbits live as long as 10 years with proper care.