Income Tax refund: Last name different. How can you cash your check under the new legal name?

I was born Galaviz since my father would not claim me. Later on he did and we always had problems changing my last name. I recently worked for walmart and they used my Galaviz last name instead of my "Gonzalez" my state ID is gonzalez, I graduated with Gonzalez and everything! Its just my SSN. Tax time is here and I do not know if I will be able to cash my check? I don't know what to do. =/ Any suggestions? And if I do manage to change my last name, will I still be able to cash my check as the name galaviz if I had my ssn name changed to gonzalez? Please help out!