First, please make sure you are typing your email in correctly. If you are sure you are using the correct email and we cannot find your account, then please just click on the link to Sign Up link and create a new account. It’s possible you haven’t ordered in awhile and your account was disabled or your account was disabled for another reason (e.g. you created a duplicate account with the same email). So creating the account again, will enable it again.
Refer to this post Help with Sign In and Sign Up on DDSGadget for additional information on signing and signing up.