Bitcoin Forum

If ever I lose a certain amount of Bitcoin (large or small), how can I  track it down or claim it back? Who should I contact?

You can track them on the blockchain using any block explorer. If they are stolen, the coin will most likely be sent to a coin mixer which means it is virtually impossible to track them.

What do you mean with losing it? Sending to other address not owned by you?
It's almost impossible, you can try to google that adress but if the owner wants to stay anonymous, then there is no way at all.

Depends what do you mean by lost. If someone steals your Bitcoin you can check on the blockchain and thats all. You can't claim it back, unless you catch the hacker but they are usually smart enough in the first place to use Tor or something.

If it's lost you can check it on blockchain however if it's been stolen there is not anything much you can do about it as it can not be tracked back as anyone who hacks and steals has always got their tracks covered.

Basically the same as if you lose a dollar bill on the street. Whether you get the bitcoin back depends how you lost it and also luck.

It isn't nearly the same, you can still track the address on blockchain an maybe try asking for it by note on small transaction, and if it was mistake or something along that, then it could work.
OFC if it wasn't mixed already  ::)

I'd say it is a bit more difficult than losing a dollar bill.  :)

How when you have info of everybody who picked whose dollar bills on site blockchain.info? :)

Bitcoin transactions are irreversible. So unless the hackers/scammers send you back the bitcoin (may be under threats or for whatever reasons), there is no way you can get it back.

If you have been hacked, you should check your machines for malware and store your bitcoin in a better way (like in an offline wallet).
If you have been scammed, you should learn to use escrows and be careful with "too good to be true" trades.
If you have lost your own wallet file, you should remind yourself to make backups next time.

Backup your wallet if your computer could crash and if someone stole them there is no way to get them back.

And to be clear, there is no central authority in bitcoin. There is no one who can roll back a transfer or tell you something you can't find for yourself on a website like https://blockchain.info/ .
You are solely responsible for doing your own security with bitcoin. Its a sad truth that even the police will be very little help, as they will have no idea what your talking about.

The best you can do is build awareness for others as I did.

Luckily, I received what was lost from the person, unfortunately most people will never get the same positive result. If it is a scammer - theres several approaches like compensating a certain amount, and give a small reward for doing so.. which may have them turn in your bitcoin and keep a still left.

Is there a place where we can complain or just ask some help? Just to guide us?

I don't think you understand what decentralized means...   :-\

You contact the CEO or Bitcoin Mark Karpeles.

Joking aside BTC requires the user to have a little computer knowledge about how to secure your coins.  Until a relatively foolproof and cheap device is made to secure coins the due diligence is on the part of the coin owner.

There is absolutely no such thing. No bitcoin dot com, no authority whatsoever. Of course if you come here and complain you may get some sympathy. We all worry about criminality and accidentally sending to the wrong address.
It may seem harsh to have to do your own security. But the fact that no one can really do anything about your transactions IS part of the security.

Everyone is responsible of his loses/wins, thats the beauty of Bitcoin. No other monetary system allows for this.

You should make a post in the scam accusation section https://bitcointalk.org/index.php?board=83.0 to warn the others and possibly discuss with other victims, but there is no way you can revert the confirmed bitcoin transactions.

How did you lost those coins ?

Transactions are irreversible. And if you lose your private keys, no way to get your coins.

Only way would be find the private key of the coins or make the other part send them back

Or you can try to generate the same private key, but probably it will take more than trillions of years.

you can't do anything
bcoz someone who stolen them should already know how to be Anonymous , and use them

OP's question is "If ever ...", so I am pretty sure he haven't lost any of his bitcoin yet. :)

and that is why bitcoin will hardly ever become mainstream.
the same thing that bitcoin takes most pride in, is its biggest weakness.
shame..

Thats why i split my coins on different wallets in case

If you are a realist, any bitcoins online on a networked computer can be stolen/lost. The safest bitcoins are offline paper wallets in a safe that's cemented into the ground with an honest 24 hour guard  :D

And what wallets is that?

Maybe you can post screenshot about what happened to warn everyone about who the scammer is.

I just lost 0.1 of a bitcoin wallet blockchain and it can not go back because there is no contact to report  :'(

Yup, bitcoin is decentralized and so no one can stop a tx from going through or revert a confirmed tx. And that is exactly the biggest selling point for bitcoin.

you can use different online wallets like coinbase, blockchain and ofc Bitcoin Client etc..

You can track it at http://www.blockchain.info but reclaiming them may not be an easy task...

If there is a malware in your pc, your bitcoin on your Coinbase, blockchain.info, Bitcoin Core wallet could all be gone.
So it is better to store bitcoin in an offline wallet.