Back several ubuntu versions ago I could resize the screen using Ctrl + Alt + - (For higher resolution) OR Ctrl + Alt + + (For lower resolution).
Now they do not seem to work. How can I add them again for resolution change.
I'm pretty sure this feature is gone since Bullet Proof X. However:
You can create short cuts (System → Preferences → Keyboard Shortcuts) to change your resolution:
Have a look at System → Preferences → Monitors to see your available modes, in my case there are four, from 640×480 up to my native resolution
You can now use
xrandr -s 0to
xrandr -s 3to change to one of them.
It's not exactly the same as the old +/– business, but it works rather well.
To add a short cut, in the Keyboard Shortcut settings, click add, choose a name, like 'First Resolution', a command like
xrandr -s 0, and hit Apply. Then click the short cut cell, where it says Disabled and press, for example, Ctrl+Shift+Alt+0 (my preference).
Note: this works on any graphics card, not just NVidia's.