When you delete a document from a Document Library, it isn’t gone forever. The document just moves to a holding place in your site – the Recycle Bin.
To restore a document from the Recycle Bin to its original location:
1) Click the Recycle Bin link in the left navigation pane.
2) Place a check mark next to any files you wish to restore.
3) Click the “Restore Selection” link.
Note: Items that were deleted more than 30 day(s) ago will be automatically emptied.