Hereof, can you miss namaz if you are ill?
Sickness is no excuse for prayer. When you are sick, depending on how hard, you can pray in sitting, laying or just with your eyes. But you have no excuse for missing it intendedly.
Secondly, can you do tayammum on a wall? It is permissible to do tayammum on walls or vessels made of clay, so long as they are not painted. If they are painted, tayammum is not valid unless there is dust on them. This means that you can pray without wudu or Tayammum.
Simply so, when can a person do tayammum?
Circumstances when tayammum is necessary
When obtaining water is hazardous or prohibitively expensive. When using water poses a health risk. When the water available is impure. When you don't have potable water.
What do Muslims pray when sick?
Whenever the early Muslims became sick, they sought the advice of the Prophet Muhammad himself. It is related that when someone fell ill, the Prophet would recite one of these du'as for them. Allahuma rabbi-nas adhhabal ba'sa, ashfi wa entashafi, la shifa' illa shifa'uka shifa' la yughadiru saqama. Oh Allah!
