can't access touchscreen settings.

i want to change my touchpad settings. there used to be an icon on my taskbar that i could click and it would open up my touchpad settings. now that icon is gone and it does not come back when i restart my computer. when i go to control panel-mouse; there are no options on any panel for the touchscreen. how do i adjust the settings on my touchscreen? i have an Inspiron 640m / E1405