Alt + Tab is the combination to switch between running programs. Also, if I hold alt after pressing tab once I can then use the arrow keys to go right or left and select the program I need.
But all of a sudden, without making any changes, when I click Alt + ← or → I get the prompt to log in to a new shell on tty3, tty4, tty5 etc.
Why did this happen and how can I change it to the old behavior?
This solved my problem:
My keyboard was in “Unicode (UTF-8) mode”. The above command will set your keyboard mode to “raw (scancode) mode”
Thanks to DK Bose