Problems with catcha to log to admin area


Somebody asked me to handle his drupal website.

I’ve got the files, I’ve got the copy of DB content, everything.
So, I’ve set up a Virtual Box machine with ubuntu server, and everything needed. Site does work on my local copy, except that I cannot get access to admin backend because of a captcha that they put in user form login.

Any idea to direct me to what I have to do (in DB or in files) so that this captcha doesn’t cause any more problem ?

I tried to set up drush and execute the instruction to disable recaptcha module, and to clear cache also, as I’ve read somewhere cache could be a problem, but then, I loose some connections to essentials CSS and JS and the site is no more available.
I also tried to configure an API key for myself in Google Account, and I tried to change API values in DB (table variable), but it seems that it doesn’t work : Captcha always give an internal error.

I’m slowly going on loosing my hairs !

Thanks for any advice.

Drupal version: