Even when able to recover account or blog access properly - using a registered email address or telephone number - Google may ask more questions, to verify identity. Some (would be) blog owners,in Blogger Help Forum: Get Help with an Issue, report that more secrets are required.
I provided my email address - and after I got the recovery email, I was asked when the email account was setup!and
After I gave my home phone, I was asked for a list of my other Google accounts!Apparently, Blogger / Google Security is trying even harder, to prevent blog theft.
Blogger is being more and more selective, in providing account / blog recovery - and is requiring secrets that not everybody can remember, as easily as they wish.
Google now requires redundant secrets to verify account ownership.
Some blog owners, even after being able to use an email address or phone (text / voice) number for token transmission, are still asked to provide additional secrets. Being asked to list other Google service accounts (GMail, Picacsa, YouTube) - and to provide approximate dates when accounts were opened - is annoying a few blog owners.
An alternative here might be Google 2-Step Verification - or use of a physical devices like a USB key, which you carry with you always.
Research the obscure account history details, before you start.
If you are preparing to request recovery of your Blogger account - or your blogs - you might do yourself a favour, by doing some research, first. Either your own email accounts - or possibly your friends email accounts - can be mined for valuable details.
If you try to fly by the seat of your pants, and guess the answers, you'll be relying on your memory. If you're here because you forgot your account name or password, are you really going to trust your recollection of when you opened your YouTube account?
Eventually, Google will use stress analysis, to verify righteous recovery.
It doesn't take too much imagination, to see the recovery process judging you by how many details you get wrong - or how long you take to answer. If you make mistakes - and keep requesting recovery - repeated requests may make you look like a hacker, trying a persistent, brute force attack.
Do your research - even plan the recovery process - before you start. It may take longer to recover your account - but you'll do it in a more relaxed manner. And being more relaxed, you'll make less mistakes.
And less mistakes leads to recovery, sooner.