Reset forgotten password in CQ5.4

The Problem

The administrator password has been forgotten for a CQ5.4 instance.

For CQ5.5 click here
For CQ5.6 click here

The Solution

Go to /crx-quickstart/server/etc/server.xml

find the <admin> node, and replace the whole fragment with

<admin>
<crypt>adpexzg3FUZAk</crypt>
</admin>

Your password should be reset to admin:admin again.