Hello , sorry about your problems. My name is Marco and I will do my best to help you.
Have you tried to take those that the DELL site offers?
If not, go to the link below, click on "Find Drivers" and click on "show all".
Go download "Dell Touchpad Firmware Application"
Uninstall the one you have and replace it with this one.
https://www.dell.com/support/home/en-ca/product-support/product/inspiron-15-3511-laptop/drivers
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Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.