Anki back of basic card

I changed the template and now my cards dont work i would like to reverse the changes to basic

Caught exception:
Traceback (most recent call last):
File “aqt\taskman.py”, line 87, in _on_closures_pending
File “aqt\taskman.py”, line 59, in
File “aqt\taskman.py”, line 76, in wrapped_done
File “aqt\clayout.py”, line 798, in on_done
File “concurrent\futures_base.py”, line 432, in result
File “concurrent\futures_base.py”, line 388, in __get_result
File “concurrent\futures\thread.py”, line 57, in run
File “aqt\clayout.py”, line 794, in save
File “anki\models.py”, line 93, in save
File “anki\models.py”, line 237, in update
File “anki\rsbackend_gen.py”, line 422, in add_or_update_notetype
File “anki\rsbackend.py”, line 256, in _run_command
anki.rsbackend.InvalidInput: InvalidInput { info: “attempt to save stale notetype” }

You may need to restart Anki:
https://faqs.ankiweb.net/when-problems-occur.html

If you can reliably trigger that message in the latest Anki version, please let us know what steps you’re taking.