I need help...Please...computer problems?

i have a problem with my internet explorer. it will not close no matter what i do! if i do ctrl/alt/del nothing happens....i dont even have internet explorer in my uninstall/change/repair option in my controll pannell! i can not even turn my computer off with the shut down option. the internet makes a dinging sou7nd if i try to close it like norma....... HELP PLEASE!!!!!!!!!!!!!!!!!!