Not sure why by I cant throw any bombs nor shoot a crossbow . I used to push middle button on mouse and a dot would appear and i could aim now nothing is it something I am doing wrong??

A quick press of the middle mouse button will auto-shoot, while holding it down will allow you to aim and it will shoot when you let go.

If that isn't working for you, check your keybindings to ensure they have not changed. If all good, ensure your game, DLC package and expansions are updated to the latest versions.