user78: Version 0.6 introduced automatic client localizations. Personally, I hate using programs in Hebrew, and prefer English, but the client didn't ask for my preferences on this matter and just switched to Hebrew.
How can I change the interface language back to English?

user659: I experimented a little in Linux to see what environment variables were affecting the choice of language:
$ env | grep -e LANG -e LC_ALL
LC_ALL=en_CA.UTF-8
LANG=en_CA.UTF-8
LANGUAGE=en_CA:en
$ LANG=de_DE ./bitcoin-qt --help 2>&1 | tail -1
  -?                 This help message
$ unset LC_ALL
$ LANG=de_DE ./bitcoin-qt --help 2>&1 | tail -1
  -?                 Dieser Hilfetext
$ LC_ALL=C LANG=de_DE ./bitcoin-qt --help 2>&1 | tail -1
  -?                 This help message
$ LANG=de_DE.UTF8 ./bitcoin-qt --help 2>&1 | tail -1
  -?                 Dieser Hilfetext
$ LANG=en_US.UTF8 ./bitcoin-qt --help 2>&1 | tail -1
  -?                 This help message

So it seems that making sure LC_ALL isn't set, and having an environment variable LANG=en_US.UTF8 will cause it to use English.
Alternatively, set LC_ALL=en_US.UTF8, but then everything will be USA-ish - you'll see American date formats, dots instead of commas for decimal points, etc.
The last time I used Windows you could set environment variables by going to the Control Panel, opening the System control, going to the Advanced tab, and clicking on Environment Variables.  I don't know if that's changed in recent years though.

user202: Start bitcoin with the -lang option ie bitcoin-qt -lang=en_US

user1507: Close the Bitcoin client and add this line:
lang=en

On a line by itself to the end of the file:
C:\Users\YourUserName\AppData\Roaming\Bitcoin\bitcoin.conf
(Replace "YourUserName" with your windows user name.)
Now restart the Bitcoin client.  Done!

user575: EDIT: The correct solution was provided by Matt Corallo but was somewhy deleted. Use the command line argument -lang=en_US.
As far as I know, QT chooses which language to use based on the OS settings. So I think the first thing to try is to configure your OS not to use a Hebrew interface.
If that fails, you should try to figure out how to disable localization in QT circles, since bitcoin-qt's localization inherits completely from QT.
If all else fails, you can recompile without the language in question.

78: <p>Version 0.6 introduced automatic client localizations. Personally, I hate using programs in Hebrew, and prefer English, but the client didn't ask for my preferences on this matter and just switched to Hebrew.</p>

<p>How can I change the interface language back to English?</p>
 659: <p>I experimented a little in Linux to see what environment variables were affecting the choice of language:</p>

<pre><code>$ env | grep -e LANG -e LC_ALL
LC_ALL=en_CA.UTF-8
LANG=en_CA.UTF-8
LANGUAGE=en_CA:en
$ LANG=de_DE ./bitcoin-qt --help 2&gt;&amp;1 | tail -1
  -?                 This help message
$ unset LC_ALL
$ LANG=de_DE ./bitcoin-qt --help 2&gt;&amp;1 | tail -1
  -?                 Dieser Hilfetext
$ LC_ALL=C LANG=de_DE ./bitcoin-qt --help 2&gt;&amp;1 | tail -1
  -?                 This help message
$ LANG=de_DE.UTF8 ./bitcoin-qt --help 2&gt;&amp;1 | tail -1
  -?                 Dieser Hilfetext
$ LANG=en_US.UTF8 ./bitcoin-qt --help 2&gt;&amp;1 | tail -1
  -?                 This help message
</code></pre>

<p>So it seems that making sure <code>LC_ALL</code> isn't set, and having an environment variable <code>LANG=en_US.UTF8</code> will cause it to use English.</p>

<p>Alternatively, set <code>LC_ALL=en_US.UTF8</code>, but then everything will be USA-ish - you'll see American date formats, dots instead of commas for decimal points, etc.</p>

<p>The last time I used Windows you could set environment variables by going to the Control Panel, opening the <code>System</code> control, going to the <code>Advanced</code> tab, and clicking on <code>Environment Variables</code>.  I don't know if that's changed in recent years though.</p>
 202: <p>Start bitcoin with the -lang option ie bitcoin-qt -lang=en_US</p>
 1507: <p>Close the Bitcoin client and add this line:</p>

<pre><code>lang=en
</code></pre>

<p>On a line by itself to the end of the file:</p>

<p>C:\Users\YourUserName\AppData\Roaming\Bitcoin\bitcoin.conf</p>

<p>(Replace "YourUserName" with your windows user name.)</p>

<p>Now restart the Bitcoin client.  Done!</p>
 575: <p>EDIT: The correct solution was provided by Matt Corallo but was somewhy deleted. Use the command line argument -lang=en_US.</p>

<p>As far as I know, QT chooses which language to use based on the OS settings. So I think the first thing to try is to configure your OS not to use a Hebrew interface.</p>

<p>If that fails, you should try to figure out how to disable localization in QT circles, since bitcoin-qt's localization inherits completely from QT.</p>

<p>If all else fails, you can recompile without the language in question.</p>
