Go do Device settings > Mouse > Check to see if an extra mouse is installed you do not use and check to see if there is a ? in front of it. Disconnect it and if there is a driver for the mouse, uninstall it and restart windows. Plug the mouse back in.
Also,
Try plugging the mouse in a different USB port. If your using a port splitter, get a new one,
Also.
Check mouse wheel settings. how many pages does it scroll down. if its a high number it will likely auto scroll. Its a life hack for scripters that always work from the bottom of the page.
Also
Any PlayStation controllers or X Box Controllers connected to your PC... Disable or uninstall
Also
Check to see if your End Key is stuck on the keyboard... Turn keyboard upside down and give the key a flick of the finger.
Also
Mouse wheel may be loose, Disconnect mouse and open it up. check the spring.
All else fails? you need a new mouse.
If its a mouse PAD? Uninstall the hardware and restart windows... should auto reinstall the mouse bad devise.
hope this helps.