I'm sorry about the issue. Was the touchpad working previously?
Does your Lenovo G50 laptop have windows 7, 8, 8.1, or 10, etc.?
Can you please press the key F6 on the keyboard in order to enable / disable the touchpad?
; if needed, press at the same time the two keys Fn and F6 on the keyboard in order to enable / disable the touchpad.
Please reply at the box below in order to continue troubleshooting. Thank you.