That's why its always advisable to route your downloads to other drives instead of C.
Just have the system related components alone in C drive.
If you have updated to Win 10, just follow this so that the problem won't be repeated in future.
*www.howtogeek.com/245706/how-to-ch...-for-saving-documents-and-apps-in-windows-10/
For recovery, you can try Recuva -Deep scan mode, and leave it overtime depending on the storage.