If your Nvidia drivers are “locked” in your Additional drivers tab after the installation of Ubuntu 21.04 this might fix the problem.
After installing Ubuntu it might happen that under the Software & Updates -> Additional drivers tab the NVidia drivers are “locked” to “unlock” them open a terminal window (press Ctrl+Alt+T) and copy and paste the command line below in the terminal window.
sudo ubuntu-drivers autoinstall
When installed reboot your system and the NVidia drivers should be “unlocked”.
