user87198: I am new to the whole Bitcoin thing, and I am having my first attempt almost going sour. I lost where I created my wallet. I have my Bitcoin address and only 11 of my mnemonic seed phrase words (of 12). I attempted using a word I thought was it and then recovered a wallet on bread wallet, but after sync in, it was still zero balance for hours. I contacted the support group and they told me that I had probably made a mistake.
What can I do?

user63872: If you are missing just one word from a 12-word seed phrase, and you know the position of the missing word, then chances are you'll be able to recover your wallet. As Martin mentioned, if you are missing multiple words, or you do not know the position of the missing word, then the number of possible combinations increases greatly, perhaps to the point of it being computationally infeasible. 
Here is a link to the BIP39 word list. If you remember anything about the word (eg, you think it started with an "a"), then you could just manually try recovering a wallet with each word that matches your suspicion (in combination with the rest of your seed phrase).
To run the entire list, you'll probably want to automate the process using some software to quickly iterate through the list. 

user76567: If you are missing the first word and you know the rest of the 11 words, there are 2048 possible mnemonics but only ~128 of them are valid.
Using Python and this library you can print all the valid ones with this simple script:
from cryptotools.BTC.HD import check, WORDS

phrase = "{x} decrease enjoy credit fold prepare school midnight flower wrong false already"

for word in WORDS:
    mnemonic = phrase.format(x=word)
    if check(mnemonic):
        print(mnemonic)

The output is:
alcohol decrease enjoy credit fold prepare school midnight flower wrong false already
alien decrease enjoy credit fold prepare school midnight flower wrong false already
ancient decrease enjoy credit fold prepare school midnight flower wrong false already
animal decrease enjoy credit fold prepare school midnight flower wrong false already
apple decrease enjoy credit fold prepare school midnight flower wrong false already
baby decrease enjoy credit fold prepare school midnight flower wrong false already
bamboo decrease enjoy credit fold prepare school midnight flower wrong false already
become decrease enjoy credit fold prepare school midnight flower wrong false already
blanket decrease enjoy credit fold prepare school midnight flower wrong false already
body decrease enjoy credit fold prepare school midnight flower wrong false already
...

Then you can try them one by one to a wallet that support BIP39. Obviously change the last 11 words in my example with your words.
Good luck!

87198: <p>I am new to the whole Bitcoin thing, and I am having my first attempt almost going sour. I lost where I created my wallet. I have my Bitcoin address and only 11 of my mnemonic seed phrase words (of 12). I attempted using a word I thought was it and then recovered a wallet on bread wallet, but after sync in, it was still zero balance for hours. I contacted the support group and they told me that I had probably made a mistake.</p>

<p>What can I do?</p>
 63872: <p>If you are missing just one word from a 12-word seed phrase, and you know the position of the missing word, then chances are you'll be able to recover your wallet. As Martin mentioned, if you are missing multiple words, or you do not know the position of the missing word, then the number of possible combinations increases greatly, perhaps to the point of it being computationally infeasible. </p>

<p><a href="https://github.com/bitcoin/bips/blob/master/bip-0039/english.txt" rel="nofollow noreferrer">Here is a link to the BIP39 word list</a>. If you remember anything about the word (eg, you think it started with an "a"), then you could just manually try recovering a wallet with each word that matches your suspicion (in combination with the rest of your seed phrase).</p>

<p>To run the entire list, you'll probably want to automate the process using some software to quickly iterate through the list. </p>
 76567: <p>If you are missing the first word and you know the rest of the 11 words, there are 2048 possible mnemonics but only ~128 of them are valid.</p>
<p>Using Python and <a href="https://github.com/mcdallas/cryptotools" rel="nofollow noreferrer">this</a> library you can print all the valid ones with this simple script:</p>
<pre><code>from cryptotools.BTC.HD import check, WORDS

phrase = &quot;{x} decrease enjoy credit fold prepare school midnight flower wrong false already&quot;

for word in WORDS:
    mnemonic = phrase.format(x=word)
    if check(mnemonic):
        print(mnemonic)
</code></pre>
<p>The output is:</p>
<pre><code>alcohol decrease enjoy credit fold prepare school midnight flower wrong false already
alien decrease enjoy credit fold prepare school midnight flower wrong false already
ancient decrease enjoy credit fold prepare school midnight flower wrong false already
animal decrease enjoy credit fold prepare school midnight flower wrong false already
apple decrease enjoy credit fold prepare school midnight flower wrong false already
baby decrease enjoy credit fold prepare school midnight flower wrong false already
bamboo decrease enjoy credit fold prepare school midnight flower wrong false already
become decrease enjoy credit fold prepare school midnight flower wrong false already
blanket decrease enjoy credit fold prepare school midnight flower wrong false already
body decrease enjoy credit fold prepare school midnight flower wrong false already
...
</code></pre>
<p>Then you can try them one by one to a wallet that support BIP39. Obviously change the last 11 words in my example with your words.</p>
<p>Good luck!</p>
