Just joined blockchain network?

[somus89]

Where to get Personal security key, which will help me if I loose my 2Key related app?

[achow101]

Your questions is incredibly vague. Can you please be more specific? Can you tell us what wallet software or service you are using?

[blo8i]

Where to get Personal security key, which will help me if I loose my 2Key related app?

It depends of your wallet. If you downloaded the QT, go to help-about-debug-console and write dumprivkey. Another option is to save your wallet.dat . This is only about backups.

If your using wallets like electrum or multibit we're just changing the story right now.

If you're using an online service is good to use 2fa as you asked in the OP.

[NeuroticFish]

Where to get Personal security key, which will help me if I loose my 2Key related app?

I assume that you talk about 2FA on blockchain.info wallet.
When you enable 2Fa you should (and I hope that blockchain.info wallet has it like many others) find a "secret" string. That's the one you have to write down and keep safe, since with that you can re-create the 2FA.