Most likely, all you need to do is adjust the screw or knob on the opener that controls where the door stops, both when it opens and when it closes. However, it is also possible that, if your opener uses a geer (wheel) with teeth to move a bicycle-like chain, that some of the teeth may have broken off, causing the chain to slip.
BTW, one can buy replacement remotes from whoever manufactured your opener, or third-party remotes, online or at Home Depot or Lowes. I installed a remote keypad outside of my garage, so I can open+close it from outside the house.