To solve the issue it is enough to delete the custom customer.xml used by your theme in app/design/frontend///layout/, so default layout shipped with base theme (in app/design/frontend/base/default/layout/customer.xml) will be used.
Or the custom customer.xml can be updated to include the following section:
<customer_account_resetpassword translate="label">
<label>Reset a Password</label>
<remove name="right"/>
<remove name="left"/>
<reference name="head">
<action method="setTitle" translate="title" module="customer">
<title>Reset a Password</title>
</action>
</reference>
<reference name="root">
<action method="setTemplate">
<template>page/1column.phtml</template>
</action>
<action method="setHeaderTitle" translate="title" module="customer">
<title>Reset a Password</title>
</action>
</reference>
<reference name="content">
<block type="customer/account_resetpassword" name="resetPassword" template="customer/form/resetforgottenpassword.phtml"/>
</reference>
</customer_account_resetpassword>