I was informed, by lawyer not to sign severance package, because of legal reason. I lost the case, does that mean I loss my severance pay?

Not sure what you are saying.  What case?  Did you sue the company for something?  If you were offered a severance package, then you probably had a limited amount of time to sign it and accept the severance benefits.  If the time to accept has expired, then you cannot accept it unless the company decides to offer it to you again.