I'm using the Blockchain app on my phone.
You should probably stop using blockchain.info or their app. They have a reputation for
not writing very good software.
You are going to need to provide more details about what happened before we can tell you how it happened.
When did you receive these bitcoins? What transaction did you receive them with? What address did you receive them at?
It looks like the person that provided you with the bitcoins
might have scammed you.
The bitcoins that you are pointing out in transaction 501665c6189a132b00c8c340074345dc8a01dd56cb9308d0bb2f0b42cfa677fb had a competing transaction (often called a "double-spend atempt").
The confirmed transaction that you pointed out spends 0.6888554 BTC providing 0.232828 BTC to 1NZaJa3u3NoC9HVJHWrSL4ZTWNeDeUYieY on 2017-05-20 at 07:41:44 UTC, with the remaining 0.4557562 BTC going back into a wallet as change at address 13UtjgEMdWuBCcr82ww9rqhD4MhTJRc4q3
The following transaction spends those exact same 0.6888554 BTC:
e0361bcf7931034ab7c0471d1a4f17cf41f164d3080274e690ae68f5f9cbcd41
This other transaction provided 0.20146 BTC to 1QGZdp5HJS9mSPhzYQUUuoFzBevsjSzcPB on 2017-05-20 at 03:13:58 UTC, with the remaining 0.48709708 BTC going back into a wallet as change at address 13UtjgEMdWuBCcr82ww9rqhD4MhTJRc4q3
Did you send (or receive) either of these transactions?