I have been unable to login to my virgin mobile account for a very long time - maybe never. It doesn't recognise any email address or any password. It doesn't recognise my mobile number, surname and postcode. When I try to register from scratch it asks me for a security answer, but doesn't show the question. When I try to email Virgin it asks me to login - which I clearly can't do!
I am going round in a loop. I am not willing to phone Virgin because from past experience that involves many, many very long calls.
It sounds like you don't have an online account for your mobile number.
When trying to register from scratch, enter your customer center password when it asks for your security answer. This is the word that you give the agent when speaking to them. Unfortunately if you can't remember this word, then your only option is to call 789 and, after passing security, you can set up a new password with a security answer. You can then go through the registration process again.