my mac is not taking screenshots

are you sure the screenshots are not being created, but rather going to an unexpected location?

you can use the keyboard shortcut "shift-command-5" to bring up the recording controls. then choose "options".

and then, in those options, check the "save to" location to see where the screenshot went.

My iMac with numeric keypad works only if with the 3 on the KB, not the numeric pad and the shot is automatically saved to my desktop. The only display image is a small momentary one bottom right on the screen.

Shift + Command + 4 brings up a "target acquisition" marker that allows me to select a given area. Once selected the shot is automatic to the desktop.

I prefer the screenshot utility in LaunchPad > Other.