i lost all my muscle when i hurt back am working out again but can't seem to tighten skin do i lift heavy or lots of reps up my protein or what need help

Preparation H helps also the elastic waist bands when used every day for an hour or so seem to tighten up the waist area ,use it duiring training or cardio ,some will say its only water loss but using it day after day does in fact tighten up the skin because of the water loss .