Moving website back to Zen Cart

[Lance8]

My client referred a friend who had turned her website over to her son. He took it off ZenCart and installed a different cart software and she hates it and wants old zen cart and template back.
Before I say yest to this job, what steps should I follow to make this transition back to her previous Zen Cart and files? Will I need to upload a new ZenCart?

Thanks

[Ajeh]

What shopping cart was it switched to?

What Zen Cart version was it before the switch?

What Zen Cart version are you wanting to switch back to?