So you are unlikely to succeed. "
Title" of the PDF can be assumed that
the first 14 bytes.
The first line is the signature PDF and the version number, the second indicates that the file contains binary data ( 4 bytes with ascii codes above 128).
The most important information is stored at the end of file,
before %EOF:
Address cross-reference table, and before this trailer, which contains the table size and number of the root object (catalog) in the structure of the document.
As well as the address of the previous cross-reference table if they are a few in the file.
To restore a file you can in several ways. Or an internal tool such as Adobe PDF Toolkit, or third-party tools both paid and free. You can choose any what's good for you. I personally use PDF Repair Kit in those cases when in open-source software PDF Toolkit cannot repair damaged pdf.
http://www.adobepdf.repair/