Extracting value from External xml based on some rule in xsl - xslt-2.0

Question

This is input xml input.xml
<root>
<bodytext>
<remotelink refptid="HKBL1.0001.lohk.CAP65">some text</remotelink>
<remotelink refptid="HKBL1.0001.lohk.CAP199999">some text</remotelink>
</bodytext>
</root>
This is Prop.xml
<?xml version="1.0" encoding="utf-8"?>
<properties>
<code dpsi="0BZG" docid="asdww">HKBL1.0001.lohk.CAP65</code>
<code dpsi="0BZH" docid="navin">HKBL1.0002.aohk.CAP383</code>
<code no="3">345</code>
</properties>
This is desired output
<root>
<bodytext>
<remotelink refptid="HKBL1.0001.lohk.CAP65" dpsi="0BZG" docid="asdww">some text</remotelink>
<remotelink refptid="HKBL1.0001.lohk.CAP199999">some text</remotelink>
</bodytext>
</root>
IF prop.xml code/text matches remotelink/#refptid than copy attribute of prop.xml to remotelink otherwise no changes in remotelink.
This is the XSLT I have written. So far I am not getting result for unmatched condition:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:fn="http://www.w3.org/2005/xpath-functions" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xlsx="http://www.stylusstudio.com/XSLT/XLSX" xmlns:spml="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:saxon="http://saxon.sf.net/" version="2.0">
<xsl:template match="#*|node()" name="root">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="remotelink[#service='DOC-ID']" name="t-remote">
<xsl:variable name="refptid" select="./#refpt"/>
<xsl:variable name="path" select="doc('file:/C:/Users/DalalNS/Desktop/xslt/prop.xml')"/>
<xsl:for-each select="$path/properties/code">
<xsl:choose>
<xsl:when test="./text()=$refptid">
<xsl:element name="remotelink">
<xsl:attribute name="DOC-ID" select="./#docid"/>
<xsl:attribute name="dpsi" select="./#dpsi"/>
<xsl:attribute name="refpt" select="$refptid"/>
</xsl:element>
</xsl:when>
<xsl:otherwise>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each>
<xsl:if test="./#docrefid"/>
</xsl:template>
</xsl:stylesheet>

Answer 1

<xsl:template match="remotelink[#service='DOC-ID']"> will never never be triggered, there's no service attribute on the <remotelink> element. Moreover, you don't retrieve the correct attribute (refpt instead of refptid)
This XSL transformation should do the job:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:fn="http://www.w3.org/2005/xpath-functions" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xlsx="http://www.stylusstudio.com/XSLT/XLSX" xmlns:spml="http://schemas.openxmlformats.org/spreadsheetml/2006/main" xmlns:saxon="http://saxon.sf.net/" version="2.0">
<xsl:variable name="props.doc" select="doc('file:/C:/Users/DalalNS/Desktop/xslt/prop.xml')/properties" />
<xsl:template match="#*|node()" name="root">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
<xsl:template match="remotelink" name="t-remote">
<xsl:variable name="refptid" select="./#refptid"/>
<xsl:copy>
<xsl:apply-templates select="#*"/>
<xsl:if test="$props.doc/code[. = $refptid]">
<xsl:apply-templates select="$props.doc/code[. = $refptid]/#*"/>
</xsl:if>
<xsl:apply-templates select="node()"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
This is the result of the transformation:
<?xml version="1.0" encoding="UTF-8"?><root>
<bodytext>
<remotelink refptid="HKBL1.0001.lohk.CAP65" dpsi="0BZG" docid="asdww">some text</remotelink>
<remotelink refptid="HKBL1.0001.lohk.CAP199999">some text</remotelink>
</bodytext>
</root>

Answer 2

I would simply define a global parameter or variable <xsl:variable name="path" select="doc('file:/C:/Users/DalalNS/Desktop/xslt/prop.xml')"/>, then set up a key <xsl:key name="prop" match="code" use="."/>, and then use that in a template
<xsl:template match="remotelink[key('prop', #refptid, $path)]">
<xsl:copy>
<xsl:copy-of select="key('prop', #refptid, $path)/#*"/>
<xsl:apply-templates/>
</xsl:copy>
</xsl:template>
that, together with your first template, should suffice.