Hello Bloooob,
We’re so sorry to hear about pinch to zoom in Adobe Reader is not working, please check for any pending updates of Adobe Reader from help>check for updates, reboot the machine after updating Adobe Reader and see if this brings any difference.
Make sure that you have the latest version of the trackpad driver/firmware installed.
Try disabling and enabling touchpad gesture and see if that helps.
For example, in Windows 10, right-click start menu > settings > devices > mouse > additional mouse options > click to change touchpad settings.
Reset the Adobe Reader's Preferences once and reboot the machine, to reset the Preferences refer to the steps mentioned in the Adobe article How to reset Acrobat Preference settings to default.
If the issue persists, please remove Adobe Reader using Acrobat cleaner tool and reboot the machine Download Adobe Reader and Acrobat Cleaner Tool - Adobe Labs
Install the latest version of Adobe Reader from Adobe - Adobe Acrobat Reader DC Distribution
What is the version of the operating system installed?
Let us know how it goes and share your findings.
Regards,
Anand Sri.