The hand on an S&W is powered by a small "mousetrap" spring inside the trigger. One end of the wire spring fits over the second pin in the hand.
If you feel up to it, here is how to maybe fix it. You already have the sideplate off, and I hope you relieved the tension on the mainspring before doing that. If not, do it now, and remove the mainspring and hammer. Then remove the rebound slide (watch the spring), and pull out the trigger and hand. The hand should have two pins, a large one that it pivots on and a smaller one. Look inside the trigger slot and you should see the end of a wire spring. Insert the hand into the trigger, and using a small screwdriver, hold the spring up until the small pin goes under it. You should see hand tension right away. Now, reinstall the trigger, easing the hand back just far enough to go into its slot. Reinstall the rebound slide and spring and the hammer and mainspring. Replace the sideplate before putting tension on the mainspring.
This may seem to be a quite a bit for a first try, but believe me, it can be done in about the same time I took to describe it.
Jim
