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Clean the registry
Maybe a program you recently installed prevents your touchpad driver from functioning properly or is responsible for the touchpad scroll not working issue. Cleaning the registry should help you solve the problem.
If your touchpad started misbehaving after you have installed or updated the touchpad driver, it is possible that something went wrong with the driver-installation process. To fix this issue you need to reinstall the driver.
Note: The best way to uninstall software (in this case, driver) is via uninstaller software. The uninstaller software uninstalls the driver (or software) and performs a thorough scan for leftovers. Sometimes, among those leftovers there are settings that will remain when you install the "fresh" driver and that might cause a conflict again.