You can regain access to your data by 
reactivating the Xero subscription, which the platform stores for a period of seven years. 

Xero Central Article - 

Reactivate your Xero organisation

https://central.xero.com/s/article/Reactivate-your-Xero-organisation#:~:text=reactivate%20your%20subscription.-,Only%20the%20subscriber%20for%20the%20organisation%20can%20reactivate%20it.,immediate%20access%20to%20your%20organisation.


Steps to Reactivate Your Xero Subscription
Only the person who was the original subscriber for the organisation can reactivate it. 
  1. Log in to Xero using your subscriber details.
  2. Go to My Xero: If you have multiple organisations, click the organisation name and select My Xero. If you only have one, you'll be taken there automatically.
  3. Access Subscriptions: Select the Subscriptions tab.
  4. Filter for all organisations: Next to the search bar, click the filter icon and select All to ensure your cancelled organisation appears in the list.
  5. Reactivate: Find the organisation name, click the menu icon next to it, and select Reactivate.
  6. Confirm details: (Optional) Select a new pricing plan if needed, then check your billing details are correct and click Confirm purchase. 
You will get immediate access to your organisation and data once the reactivation is complete. 
Important Considerations
  • Data Retention Period: Xero generally retains archived data for up to seven years to align with common business record-keeping requirements, though this may vary by region.
  • Subscription Fee Required: While Xero doesn't charge for data storage of a cancelled account, a subscription fee is required to regain access to the data when you reactivate.
  • Temporary Access: If you only need temporary access (e.g., to export data), you can reactivate the subscription and then immediately cancel it again. You will continue to have access for the one-month cancellation notice period.
  • Exporting Data: Xero recommends that customers export key data and reports before cancelling their subscription as a best practice for record-keeping. 
If you encounter any issues during this process, you can reach out for help via the Xero support page.