Recover a PDF that will not open, opens blank, or was cut short by a download that failed — and rebuild a readable file from what is left.
The viewer reports a broken cross-reference table, the file opens to a blank page, half the pages are missing, or a download stopped at 90% and the file is truncated. These are all structural problems: the pages may be perfectly intact while the index that tells a viewer where to find them is damaged. Repair rebuilds that index.
If the bytes of a page were never downloaded, no tool can invent them: a truncated file yields the pages that actually arrived. If the document was encrypted and the password is lost, repair will not bypass it — that is Unlock's job, and it needs the password.
Before repairing, try downloading the original once more from wherever it came from. Half of the "broken" PDFs in the world are simply incomplete downloads, and a clean copy is better than any repair.
It recovers what is present in the file. Pages whose data never arrived cannot be reconstructed.
Often yes — that error usually comes from the damaged index, which repair rewrites.
No. It rebuilds the structure around the existing page data.