Removing and reassembling sliding window sashes is much more simple than it may appear. To put your sliding window sashes back in place, follow the steps below:
Push the top of the exterior-facing window sash up until it sits in the outer window track (the track closest to the exterior of the window). Continue providing upward pressure and push the bottom of the window sash into place on the lower track.
Next, push the top of the interior-facing window sash into the upper track (on the interior side of the frame). While continuing to apply upward pressure, push the lower portion of the inner window sash into the lower track until it is securely in place.