Let's say I have transformed an layer/element in Photoshop and I'm well past the point of being able to undo, or it would be highly inconvenient. Is there a way to revert the transformation back to 100% size, 0° rotation, etc?
If the transformations are no longer in the History Panel, then there is no way to revert them.
The exception would be smart objects. If you transform a smart object, you can always revert the smart object to the default state.