My mail program is not loading in Sonoma 14.6 . The program doesn't load/start up. I am using a new M2 Studio

On your Mac, choose Apple menu  > Shut Down.

Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.

Press and hold the power button on your Mac until “Loading startup options” appears.

Select a volume.

Press and hold the Shift key, then click Continue in Safe Mode.

The computer restarts automatically. When the login window appears, you should see “Safe Boot” in the menu bar.

Does the problem occur in Safe Mode? 

Restart normally.

To find out if it's system wide or user specific, try this...

Open System Preferences>Users & Groups, unlock the lock, click on the little plus icon, make a new admin account, log out & into the new account.

Does it work in the new account?