How to keep the seek bar persistent even after back button is pressed and re opened player activity

Question

i am trying to create a music app. the seek bar in the media player is not working if i pressed back button and reopen the activity again.

could anybody help me to solve this problem?

here is My play pause button code

binding.playBtn.setOnClickListener {

            if (isPlaying){
                mediaPlayer?.pause()
                isPlaying = false
                length = mediaPlayer!!.currentPosition

            }else{
                mediaPlayer = MediaPlayer()
                mediaPlayer!!.setDataSource(songs[1])
                mediaPlayer!!.prepare()
                mediaPlayer!!.start()


                mediaPlayer!!.seekTo(length)
                isPlaying = true


            }

            runnable = Runnable {


                binding.seekBar.progress = mediaPlayer?.currentPosition ?: 0

                handler.postDelayed(runnable,1000)
            }
            handler.postDelayed(runnable,1000)


 }