\textbf{} is not working?

Question

I am working on a long latex(Beamer) file. Till now like 700 line.

My details setting regarding font's are,

\usepackage[utf8x]{inputenc}
\usepackage{amsmath,bm}
\usepackage{textcomp}
\usepackage{bbm}
\usepackage{dsfont}
\usepackage[normalem]{ulem}
\usepackage{amssymb}
\usepackage{mathtools}
\usefonttheme{professionalfonts}

I don't know when or how, but now in the beamer, \textbf{} command has no effect on output.

I tried to comment down

\usefonttheme{professionalfonts}

My best guess was \usefonttheme{} function stops the \textbf{} function. but while commenting \usefonttheme{}, Latex stops to generate output except for the "table of content", I also don't know why this is happening.

UPD: Here is a sample slide,

\documentclass{beamer}
%
% Choose how your presentation looks.
%
% For more themes, color themes and font themes, see:
% http://deic.uab.es/~iblanes/beamer_gallery/index_by_theme.html
%

\mode<presentation>

  \usetheme{Warsaw}      % or try Darmstadt, Madrid, Warsaw, ...\textbf{\(\(\(\)\)\)}}  

  \usecolortheme{default} % or try albatross, beaver, crane, ...
  \usefonttheme{default}  % or try serif, structurebold, ...
  \setbeamertemplate{navigation symbols}{}
  \setbeamertemplate{caption}[numbered]
\usepackage{ragged2e}
\usepackage[english]{babel}
\usepackage[utf8x]{inputenc}
\usepackage{hyperref}
\usepackage{amsmath,bm}
\usepackage{upgreek}
\usepackage{multicol}
\usepackage{textcomp}
\usepackage{bbm}



\usefonttheme{professionalfonts}



\usepackage{utopia} 
\usepackage[normalem]{ulem}
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage{mathtools}


\newenvironment{nscenter}
 {\parskip=0pt\par\nopagebreak\centering}
 {\par\noindent\ignorespacesafterend}


\title[Awesome slides]{Awesome Slides}
\author{maruf}


\begin{document}

\begin{frame}
  \titlepage
\end{frame}


\begin{frame}
    \frametitle{Table of Contents}
    \begin{multicols}{2}
        \tableofcontents
    \end{multicols}
\end{frame}


\section{Introduction}

\subsection{code code code}
\subsubsection{code}
\begin{frame}
\frametitle{Hello World}    
The quick brown fox runs over the lazy dog \textbf{ABCDEFG}.
    \begin{itemize}
        \item \textbf{asdasd}
        \item aasdasd
    \end{itemize}
\end{frame}

\end{document}

Answer 1

Loading professionalfonts here does nothing at all, because \usepackage{utopia} only modifies \rmfamily, but you're still using sans serif for the presentation.

You get the warning

LaTeX Font Warning: Font shape `OT1/cmss/b/n' undefined
(Font)              using `OT1/cmss/m/n' instead on input line 73.

which should be almost self-explaining: there is no boldface in Computer Modern Sans Serif.

If you want to use Utopia for your presentation, you also have to choose \rmfamily for the text font, which can be done with \usefonttheme{serif}. And fourier instead of utopia as you seem to be using math.

I reordered parts of your input. Don't use utf8x, it's been unmantained for a few years and utf8 is instead actively developed.

\documentclass{beamer}
\usepackage[utf8]{inputenc}

\mode<presentation>

\usetheme{Warsaw}

\usecolortheme{default}
\usefonttheme{serif} % <----------- HERE
\usefonttheme{professionalfonts}
\setbeamertemplate{navigation symbols}{}
\setbeamertemplate{caption}[numbered]


\usepackage{fourier}% <------------ not utopia 
\usepackage[normalem]{ulem}
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage{mathtools}

\usepackage{ragged2e}
\usepackage[english]{babel}
\usepackage{amsmath,bm}
\usepackage{upgreek}
\usepackage{multicol}
\usepackage{textcomp}
\usepackage{bbm}
\usepackage{hyperref}




\newenvironment{nscenter}
 {\parskip=0pt\par\nopagebreak\centering}
 {\par\noindent\ignorespacesafterend}


\title[Awesome slides]{Awesome Slides}
\author{maruf}


\begin{document}

\begin{frame}
  \titlepage
\end{frame}


\begin{frame}
    \frametitle{Table of Contents}
    \begin{multicols}{2}
        \tableofcontents
    \end{multicols}
\end{frame}


\section{Introduction}

\subsection{code code code}
\subsubsection{code}
\begin{frame}
\frametitle{Hello World}    
The quick brown fox runs over the lazy dog \textbf{ABCDEFG}.
    \begin{itemize}
        \item \textbf{asdasd}
        \item aasdasd
    \end{itemize}
\end{frame}

\end{document}