I can't go on with my thesis because of a table. Id like to colour this but without any help I'm facing some trouble. Anyone could help?
\usepackage{graphicx}
\usepackage{colortbl}
\usepackage{multirow}
\usepackage{tabularx}
\usepackage{ltablex}
\usepackage{ragged2e}
\usepackage{changepage}
\newlength{\offsetpage}
\setlength{\offsetpage}{1.0cm}
\newenvironment{widepage}{\begin{adjustwidth}{-\offsetpage}{-\offsetpage}%
\addtolength{\textwidth}{2\offsetpage}}%
{\end{adjustwidth}}
\usepackage{colortbl}
\newcommand{\undepth}[1]{%
\smash[b]{%
\begin{varwidth}[t]{\linewidth}#1\end{varwidth}
}%
}
\documentclass[12pt,a4paper,oneside,openright]{book}
\begin{document}
\begin{table}[htbp]
\centering
\caption{Fattori che influenzano i recovery rate}
\label{tab:componenticr+}
\begin{widepage}
\begin{tabular}
{p{0.15\textwidth}|p{0.15\textwidth}|p{0.3\textwidth}|p{0.3\textwidth}}
\toprule
\rowcolor[rgb]{ .188, .329, .588} \multicolumn{4}{|c|}{\textcolor[rgb]{ 1, 1, 1}{\textbf{CreditRisk+}}} \\
\midrule
\multicolumn{2}{c|}{\vspace{0.05cm} Misure per il Rischio di Credito \vspace{0.05cm}}&Capitale Economico&Applicazioni\\
\midrule
\rowcolor[rgb]{ .867, .922, .969} Esposizione&\undepth{Tasso di\\ Default}&\multirow{2}{*}{\undepth{Default\vspace{0.3cm}\\ Distribuzione di perdita}}&Approvvigionamento\\ \cline{1-2}\cline{4-4}
\rowcolor[rgb]{ .867, .922, .969} \vspace{0.03cm} \undepth{Tassi di\\ recupero}& \vspace{0.03cm} Volatilità PD&& \vspace{0.03cm} Limiti\\
\midrule
\rowcolor[rgb]{ .867, .922, .969} \multicolumn{2}{c|}{\vspace{0.05cm} CreditRisk+ Model}&Analisi di scenario&Gestione di portafoglio\\
\bottomrule
\end{tabular}
\end{widepage}
\end{table}
\end{document}

\documetclass{...}had to be first in your document example; (iii) remove all to your problem irrelevant packages; (iv)booktabsand vertical lines doesn't work well together (also coloring table rows not); (v) your example has errors. please correct them. – Zarko May 08 '18 at 17:23