I found many ecommerce cms but Magento is perfect for large scale business. Here are I found some good comparison: http://www.cloudways.com/blog/the-best-content-management-systems-cms-for-ecommerce-part-1/

If your hosting plan has backup feature so retrieve from backup source. If its not available, ask management to give the backup property of that site. If there is no response or they have not available any backup so its mean you have to start from scratch.