http://www.faa.gov/licenses_certific...ation_records/
There is a form to fill out but it says it may take 6-8 weeks. It costs $5.25 plus 5 cents per page... so $8 or so. It has copies of all written exam results, temporary certificates, 8710 forms, etc.
You can also try calling Airman Certification at (866) 878-2498. They also have a form to replace a knowledge test report but I am not sure if it works for old exams (ie. more than 24 months or for a rating already issued). Its worth a try and thats $1.
http://www.faa.gov/licenses_certific...s_replacement/