If you're trying to open the PDF file after the recovery, then there is a chance that file is actually corrupted. Typically, you use Adobe Reader to open the file, but if it gives you errors while doing it, then the file hasn't been recovered completely. Some recovery solutions only restore partial contents of a file. It's enough to just have the headers messed up for any file to render it unusable. I recommend you open the PSD file again and export to PDF once more. This way you'll have a working file without errors. It's impossible to fix the file to magically add missing content, because no app will ever do that.