Custom Ribbon uninstalled but still remains

Hello,

I restored a site collection with a backup file (.CMP file) whocontains a custom ribbon WSP definition on a server.

I tried to uninstall the custom ribbon with the following lines :

Uninstall-SPUserSolution -Identity My_Ribbon_Solution.wsp -Site http://sp_site/sites/my_site_collection/

Remove-SPUserSolution -Identity My_Ribbon_Solution.wsp -Site http://sp_site/sites/my_site_collection/

The result is that it uninstall the wsp, because I don't see it in my solutions gallery and no result is shown when I ask Get-SPUserSolution for this site collection... But the ribbon is still there...

Is somebody could give me some informations to uninstall properly a custom sandbox ribbon feature who still remains in my site collection ?

Could you give me some informations on the installation location of a custom ribbon (databases or frontend files location ???)

Thks in advance,

DkPoo.