On a desktop PC, holding down the Ctrl key and rotating the mouse wheel will make the icons larger or smaller. Perhaps you did the laptop equivalent to that. Maybe even a sticky Ctrl key.
Some Tips on how to operate touchpad like a pro.
1. Drag and Right Click.
2. Multi Files Selection.
3. TouchPad Rotation and Scaling.
4. Touchpad Scrolling.
5. TouchPad Switches Windows.