If you are referring to the 6-digit code for email verification during efiling, be sure the code is not ending up in your email's spam/junk folder or another email address you have. See this FAQ on some tips, which also includes info on how you can change the email address in your Account Settings, if you wish to use another email address.
FAQ: What if I'm having trouble with my filing verification code?
https://ttlc.intuit.com/community/security/help/what-if-i-m-having-trouble-with-my-filing-verificati...