MyEtherWallet actually gives a private key to access your password. If you have lost your key I'm sorry there is no other way to access your wallet except try to find out where you put your key. Try to find in deleted files or somewhere like this.
That is why it is highly recommended that you always have a hard copy and a soft copy back up with your wallet key and password, it is best if you always have your USB or your hard disk drive to keep your important files.