How to fix econnrefused error in mongoose?

Question

MongoDB

Hello. Literally yesterday I wrote the code, everything worked, turned on the computer today and that's what it began to give me. I have no idea why it refuses access, maybe the default port is busy with something?
Connection
mongoose.connect('mongodb://localhost/test');
string Error string

process.nextTick(function() { throw err; })
                                      ^
Error: connect ECONNREFUSED 127.0.0.1:27017
    at Object.exports._errnoException (util.js:856:11)
    at exports._exceptionWithHostPort (util.js:879:20)
    at TCPConnectWrap.afterConnect [as oncomplete] (net.js:1063:14)

I tried to change the default port (which is 27017) to another one, but I could not change the mongo.conf file, I don’t know if this really helped or not.
Thank you for your attention.