Why won't my home button work?

Hello! I have an issue with my home button on my phone. I've been having my phone for two years now. But about a year ago, I dropped my phone in a bowl of cereal and the milk got into the home button I guess. Perhaps that's the reason it won't work. I installed a home button app on my phone which I have been using since then. How can I fix it myself?Thank you for your time and help!