My visa status:
F1: Jan 2006-Jan 2008
F1 opt: Jan 2008-Dec 2008
H1b: Dec 2008 - current

My ss tax and medical tax are not exempt during the opt period.
My question is which tax form I should file?
And how can I get the ss tax and medical tax druing the opt back?

Thanks.

You will file nonresident tax return with Form 8843.

For refund of FICA taxes, You will file Form 843. It is filed separately. Read about filing Form 843: Your U.S. Tax Return: Social Security and Medicare (FICA) Taxes for Non-resident Exempt Individual (http://taxipay.blogspot.com/2008/03/non-resident-exempt-individual-social.html)