This article covers some of the most common questions asked in these forums regarding recovering Microsoft accounts.
But before I start, Microsoft has these articles Microsoft account recovery and other commonly asked Microsoft account questions:
Help with the Microsoft account recovery form - Microsoft Support
Recover your account (live.com)
How to recover a hacked or compromised Microsoft account - Microsoft Support (article)
How to recover a hacked or compromised Microsoft account - Microsoft Support (walk-through)
Account recovery unsuccessful - Microsoft Support
You forgot your Microsoft account username - Microsoft Support
Reset a forgotten Microsoft account password - Microsoft Support
You are 100% responsible for keeping your account secure. Use strong passwords and DO NOT reuse passwords on other sites. Use multiple addresses and phone for recovery or two-step verification. If you were hacked or want to change your password and update the security information, change the password first then add the new security information. Delete the old security information last.
If you have two-step verification turned on, you cannot use the recovery form. You will need to supply a second verification option. If you don't have a second verification option, you cannot recover the account. Sorry, there is no way around it.
Support personnel are not allowed to reset passwords or update security information. Don't bother trying to contact Microsoft support for assistance with password issues.
Microsoft includes this disclaimer on some of their account recovery articles.
Along with using strong passwords, encryption, security contact information and other technology to keep your content safe and secure, we have strict policies on how our advocates can help you with your account. Only you can reset your password and make security changes to your account.
I'm not going to mince words or try to sugarcoat it, but in most cases, the only correct answer for many users is "sorry, the account is gone and unrecoverable".
You are trying to log into an old Outlook.com account.
When did you last log into the mailbox? If you don't log in at least once a year, the account is inactive and purged and the only way to recover it is if you have the password - resetting the password won't work.
If you haven't accessed the Microsoft account in more than 2 years, it will be deleted (closed for good). The exact period for closure depends on when the account was created (older accounts have a longer inactive period) and the only way to know if it is still available is to send an email to the address and see if it bounces.
Microsoft account activity policy
Once closed, addresses cannot be claimed or reclaimed, or otherwise reopened.
"That Microsoft account doesn't exist. Enter a different account" message
When you attempt to sign into an account and receive a message that the account doesn't exist, it means the address is not used on an account.
If you try to create a new account using that address and the message says the account is in use, it means the address was previously used by was either deleted or the account closed by the user, or in active for more than 2 years and closed by Microsoft.
Once used, addresses cannot be reclaimed or added to another account.
If you need to get into the account because you used the address as the security address on another account or service, you'll need to use another method to get into that service.
Someone accessed your Microsoft account and deleted your address. This could be a hacker or your child.
In this case, your account is gone. Once an address is deleted from an account, it cannot be restored. (This is a policy I disagree with; addresses should be restorable for at least 7 days, up to 30 days. I've seen too many kids delete parents addresses from their Xbox or people delete an alias then realize they goofed up.)
Children need their own accounts for Xbox. While they cannot move gamer tags or games that are on your account to their own account, I've seen too many people lose their accounts because the child deleted the parent's address from his Xbox.
A hacker accessed your email account and changed the security information
This is the only scenario where you might be able to recover the account because there may be a 30 day hold on changing the security information. But you need to attempt it within 30 days of the account being hacked – the sooner, the better. Once 30 days have passed, the security changes are permanent and the hacker owns the account.
If you changed your security information, you may have the 30 day wait. Unfortunately, there is no way around it, you need to wait it out. You should be able to access email and services but can't change your password or other information.
If you were hacked or want to change your password and update the security information, change the password first then add the new security information, finally, delete the old security information.