documentclass{article}
usepackage[utf8]{inputenc}

begin{document}

maketitle
thispagestyle{empty}
newpage

section*{Abstract}
addtocontents{toc}{~hfilltextbf{Side}par}
addcontentsline{toc}{section}{protectnumberline{}Forord}

section*{Introduction}
addcontentsline{toc}{section}{protectnumberline{}Sammendrag}

newpage
tableofcontents

listoffigures
addcontentsline{toc}{section}{protectnumberline{}Figures}

listoftables
addcontentsline{toc}{section}{protectnumberline{}Tables}
newpage

pagenumbering{arabic} ´

%Several sections here

newpage
appendix
section{Appendix A}
subsection{Appendix name}

end{document}

documentclass{article}

usepackage{xparse}
newcommand{setsectiontocentry}[1]{defsectiontocentry{#1}}
letoldsectionsection
makeatletter
RenewDocumentCommand{section}{ s o m }{%
  IfBooleanTF{#1}
    {% section*
      oldsection*{#3}%
      IfValueTF{#2}
        {addcontentsline{toc}{section}{protectnumberline{}#2}}% section*[.]{..}
        {@ifundefined{sectiontocentry}
           {addcontentsline{toc}{section}{protectnumberline{} #3}}%
           {addcontentsline{toc}{section}{protectnumberline{} sectiontocentry}}%
         letsectiontocentryrelax
        }
        %{addcontentslineaddcontentsline{toc}{section}{protectnumberline{}%
           %ifcsname sectiontocentryendcsname
             %sectiontocentry
           %else
              %#3%
           %fi
         %}%
         %letsectiontocentryrelax
        %}% section*{..}
    }
    {% section
      IfValueTF{#2}
        {oldsection[#2]{#3}}% section[.]{..}
        {oldsection{#3}}% section{..}
    }%
}
makeatother

begin{document}

addtocontents{toc}{~hfilltextbf{Side}par}
section*{Abstract}

section*{Introduction}

clearpage

setsectiontocentry{ToC}
tableofcontents

setsectiontocentry{Figures}
listoffigures

listoftables

clearpage
pagenumbering{arabic}

section{First section}
section{Second section}
section*[THIRD SECTION]{Third section}
section{Last section}

clearpage
appendix
section{First appendix}
section{Second appendix}

end{document}