Restoring a refreshed sandbox in Salesforce
It might be a big problem if you have accidentally removed or refreshed your sandbox. You should know that a sandbox refreshing will delete the existing one. When you begin a refresh process you will see the message that this action is permanent and can’t be reverted back.
Activating a replacement sandbox that was created using the Refresh link completely deletes the sandbox it is refreshing. All configuration and data in the prior sandbox copy will be lost, including any application or data changes you have made. Please read the warning carefully, and press the Activate link only if you have no further need for the contents of the sandbox copy currently in use. Your production organization and its data will not be affected.
However, this’s not the all truth about the removing/refreshing sandboxes. If you have destroyed your sandbox accidentally, you have 72 hours to contact Salesforce.com support and ask them to restore your sandbox. So, you just need to create a ticket with support ASAP.
Below, you can find the justification. This is the email thread with salesforce support