mentions are temporarily disabled.
1) You'd have to show proof that you're the owner of the account
ii) Regularly to show ownership of the account you'd have to have access to the email associated to the account, which you don't have.
2) Having 250 posts is nothing, it's worthless putting effort into retrieving it.
ii) Making a new account would be beneficial to you, it gives you the chance to pick a better name (more original name at that) and you can use a secure email address along with it.