error establishing a database connection

Hello, I know this topic has been asked many times but I do not find the answer in any of them.
I started constructing a website on a local server using WAMP. However, today, I cannot access localhost/wordpress (my db) and it is said “error establishing a database connection”.

I tried to modify the wp-config file with my user data, to modify my password, etc, but nothing worked and I do not know what to do.