Black screen after deleting nvidia - главенствовал

I decided to change nvidia - главенствовал to bumblebee. I переместите the nvidia - главенствуйте, installed bumblebee and restarted the computer. Loading freezes on plymouth. Then I booted into recovery mode and uninstall the драйвер nvidia-355 and bumblebee. Thereafter, at logon screen turns black. In the middle of the screen there is в курсор, which хан not be двиньте. Ubuntu 15.10 x64