New to Magento, recovering old Magento site for client. Seeking advice 🙏🏽

Hi all – I am hoping someone can offer some advice as I am at a loss in searching for answers solo.

My client used to have a site with Magento, it has been offline for 2 years and I’m not sure if the reason it went offline. I gather there may have been a shift in platforms, as I see Magento 2 is a separate thing.

I’ve contacted Adobe Commerce with no avail. Could someone please tell me if an old site built using Magento can be revived in its current software?

Essentially I’ve been given their old url and logins to access but no longer going to working login screen.

The reason for sticking with Magento is because it integrates with their POS system (Retail Express).

Please any guidance would be very appreciated as I don’t know if Magento is a valid option, or if we need to consider a new platform like Shopify.

Many thanks! 🙏🏽