Can I get back my saved data?
It may be possible but not easy. It depends on how much data was actually erased and how much has been written since then.
Restoring deleted files on an Xbox is similar to restoring PC files. When files are deleted, they are often not actually deleted- the system just erases any reference to the file and may overwrite it when it needs to.
To get the data back, you would need to somehow connect your hard drive to a PC and access it, then run some disk rescue software on it. This might retrieve your save.