Error establishing database connection

Hello,

I had uploaded my WordPress site on a web host and it was working fine. but for the last week there was some problem with the web host and the site was down, now the web host problem has been resolved and all my other sites hosted on it are working fine except the wordpress site. The WordPress site shows an error as ‘Error establishing database connection’. Meanwhile i have not made any changes to the database files or the config file.

Thanks in advance!