Restore from backup stocked on step 1 of 3

My site is completely down, and I am now restoring fro mthe backup.
But I an stucked in the step 1 of 3. I can't start the database restore: "A database with this name already exists. By proceeding we will wipe and overwrite all existing data. We recommend creating a new database instead."
But the database is empty and are newly created. But I don't have other buttons only "Re-test connection".
How can I start the restore ?