How can I restore my wallet?
You need to put the old wallet.dat in your bitcoin data directory.

The default for Windows is:

C:\Documents and Settings\YourUserName\Application data\Bitcoin (XP)

C:\Users\YourUserName\Appdata\Roaming\Bitcoin (Vista and 7)


Then run the bitcoin client with the -rescan option.

Alternatively you can run the bitcoin client with the -datadir=&lt;location of backup wallet.dat&gt; as well as the -rescan option if you do not want to move/backup the new wallet.dat.

The default for Mac OS X is:

~/Library/Application\Support\Bitcoin



The default for Linux is:

~/.bitcoin