However, there are ways to get the move again indirectly:
* Trade: You can trade a Pokémon that knows Rock Smash to another game (like Crystal or Gold), then trade it back.
* Breeding: If you breed a Pokémon that knows Rock Smash with a compatible Pokémon, there is a chance the offspring will inherit the move.
* TM: In later generations of Pokémon games, Rock Smash is available on a TM. You can transfer your Silver save file to a newer game and obtain Rock Smash that way.
Keep in mind that these options are only available in later games or require a bit of effort. If you're playing Pokémon Silver, you're stuck with the one Rock Smash you learned from the move tutor.