Download a verified version of mss32.dll specifically tailored for GTA Vice City v1.0 or v1.1 from trusted retro gaming databases or community hubs like the GTAForums.
C:\Program Files (x86)\Steam\steamapps\common\Grand Theft Auto Vice City Download a compatible version of from a trusted source or extract it from a fresh installer. Move the new file into your game folder, replacing the existing one. put this file into C:\Windows\System32 Download a verified version of mss32