Login Loop since days

Hi,

I can’t login into WordPress anymore.
I enter the user and the password and it returns to the login again.
I checked then with a wrong password and it refused with the appropriate error message.
No user (admin, gestionnaire, customer) can’t login.
I checked the database with CPanel, every thing seems to be allright.
I desactivated all plugins and all themes with no result.
I installed a new wp-login.php from a new WordPress installation, no result.
I am running the last version of WordPress 4.9.6, the last version of woocommerce with the last version of Storefront. All in French. I can’t provide the version numbers of woocommerce and storefront as I am not capable to login.

Just to add, a customer placed an order which had been handled correctly the day after I tried to login and it failed since.

I read a lot of messages about login loop but none of them will solve my problem.

Any help would be appreciated.