can't hit anything

Hello

 

In my maps i can place but not destroy blocks or hit any mob.

My mouse is working i can click in the menu but not on maps it should be because of my computer but i Don't understand why. (I live in switzerland so sorry for my English).

I thought it was in the gamerule but didn't find anything about it. Maybe because of my bad English.

 

Thanks for readong my message and I hope you will be able to help me.