Student licence : impossible to obtain a new serial number

Hello, I try to install SW student with the SEK code shared by my teacher. I tried with my old serial number but it’s say that it’s outdated. In the download instructions, it is say that by the email I receive that I will receive the new serial number by another email but I receive nothing ! ( not in my spam too). I don’t know what to do. 
Thanks for help ! 

Edu SOLIDWORKS