Mongo connection refused



I don’t know what i did, i might have tried installing mongo again after i already installed it once, but now i get an error everytime i try to run my app (node app.js). I get the error below:

(node:6377) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): MongoNetworkError: failed to connect to server [localhost:27017] on first connect [MongoNetworkError: connect ECONNREFUSED]

Does anyone know what is the issue and how to fix it?

thank you very very much!