Hi
As its a Synaptics driver, and therefor non OEM specific.
Open device manager, there should either be an ! on the current "installed" driver, or one showing as
Other devices also with !.
There are 3 base synaptics drivers included within 7's driver store.
Whichever of the 2 options you have,
select update driver >>> Browse my computer >>> Let me pick >>> UNTICK show compatible hardware >>> try each of the drivers listed
you can safely ignore the unsigned driver warning
notes
my hp uses a synaptics ps/2 port touchpad driver, 17 0 18 25, dated 2017, which the OS picked up automatically.
check your Bios it might have a touchpad default setting thats stopping the install
UNinstall any Lenovo touchpad programs first
Roy