usb not working . I can't access to bios

hi! After having modified the bios settings (for sure I made a mistake while doing adjustements) I've no usb working. Windows starts but without keyboard neither mouse. no one of the usb port works. Even directly while powering on the lattepanda, no one of the usb port works. So I can't access to bios. How can I do to access to bios settings without keyboard. The link you gave to the previous message doesnt seem to work.

could you help? thanks