File comment history

After deleting a file all evidence of file comments are gone. Our workflow: Add PDF to file column for others to review. Others review and add comments to PDF for changes. Fixed PDF now added to file column and old file deleted (This is to stop old, incorrect info being used. Tried versions). Next happens every time, Others ask why something got changed and they are the ones requesting said change. Would love to be able to reply with screen shot of their comment.