So i am trying to create a rig. I want to make it so if i move say the arm or the eyeball, and I don't wanna have to keep undoing., how could I make it so i could just press Alt-G, and the object snaps back to where I want it?
By definition AltG, AltR and AltS will bring back the bones to their rest position, i.e. their position in Edit mode.
If you want to go back to a particular pose that is not the rest pose, you may be interested by the Pose Library that is in the Properties panel > Object Data.
You can create as many poses as you want, to create a pose, click on the "+" button, to recall a pose, click on the magnifying glass icon, to change a pose, click on the "+" button and choose Replace Existing.
Note that if you select one bone only and click on the magnifying glass, it will only recall the pose for this particular bone.