windows mobility centre

previously on my laptops taskbar at the bottom the volume control and
wireless network icon was on display in the taskbar, but now it does not
show, and when i click on the properties of the taskbar it does not allow me
to choose and click the volume and network. please can u tell me how to get
these two icons back onto the taskbar display, i have found the mobility
centre in the start menu, but want those 2 icons on the taskbar. thankyou