I dropped my phone in water

fiona Kubwalo Rice will not prevent corrosion nor repair your phone. The very first thing you want to do is to no longer try to turn your phone on. The second thing you want to do is to clean your phone. If you do not clean it properly, you are running risk of having corrosion damage in the near future. Disassemble your phone completely and clean everything, especially the logic board, connectors and cable ends with 90%+ isopropyl alcohol. Use a soft brush to gently clean every "nook and cranny". Check your board for any missing or burned components. After that replace the battery. Re-assemble your phone and re-evaluate. Let us know the exact model of your Nokia phone so we can try and help you further.