Its even impossible to restore lost private key, how much more taking lots of numbers and letters.Thats why private key is designed like that to secure your wallet from thief.If thats possible you need a long time before you got the right private key.
Possible that somebody steal your bitcoin, if you are not mindful and vigilant in your account on your wallet, experience of my friend that his coin on his wallet was gone because he send those private keys in a messenger and code of his wallet where the coins deposited as his earning in the bounty campaign, he discovered that his coins was already withdrawn.