Python Idle won't start

[snippsat]

Do this from command line and post output.

python3- V
python- V
which python3
which python

pip -V
pip3 -V

# Try start Idle like this
python3 -m idlelib

Problem try to do new install
How to Install IDLE Python
Don't know pacman package manager deal with have to search for that.

IDLE is not good,unfortunately so has Python not address this problem it has been up for debate many times.
Usually only beginner that use IDLE before they find something better.