Password Reset: Who can tell me why?

It was quite mysterious that my site suddenly stopped working this afternoon. Followed by the previous experience that the incorrect configuration of plug-ins that damp the service of Word Press, I checked all the plug-ins initially but nothing wrong. Problems seems to be more serious since the website then indicated that errors occur when connecting to the database. I logged into the background but found no clue at all. Unlike the description from some site that the database was deleted by the 000webhost.com that it remained, but the PhPMyAdmin failed to work. I was getting fully puzzled on what was happening.

But things alway turn their tables in a flash, so do my site. Occasionally I signed into the MySQL and tried to reset the password, and my sites work again! it is really mysterious that how do my password changed?

Who can tell me why do this happen? I am getting puzzled…