My cursor is on screen and i can't use M1 M2 or M3 buttons.

My cursor is where my crosshair is and when I look around it moves with the crosshair and when I use M1 M2 or M3 when not moving my mouse I then can't move the crosshair and only the cursor moves and if I do move my mouse the M1 M2 or M3 buttons will work.