[Tex/LaTex] LaTeX not compiling after switching computer

auxiliary-filescompilinginstallingtexniccentertexworks

I've changed computers recently; my project was compiling just fine previously, and on the new computer it's not compiling at all. The output is stuck at the last version I compiled on the previous computer (2015/03/04; today is 2015/04/07).

I had installed Texlive on the old pc, I was working on TeXnic Center and compiling with XeLaTeX. I've installed Texlive on the new pc, and I've re-installed separately MikTeX and GSview, but maybe I'm still missing some software? Since the project used to compile fine, I don't think the code is bad but here's my preamble just in case: 

\documentclass[a4paper,12pt]{book}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{csquotes}
\usepackage{fontspec}
\usepackage{xunicode}
\usepackage{polyglossia}
\usepackage[Latin,Devanagari]{ucharclasses}
\setmainlanguage{english}
\setotherlanguage{hindi}
\newfontfamily{\devanagarifont}{Kokila}
\setmainfont[Script=Devanagari]{Kokila}
\newfontfamily{\latinfont}{Times New Roman}
\setmainfont[Script=Latin]{Times New Roman}
\usepackage{microtype}
\usepackage{graphicx}
\usepackage{setspace} 
\onehalfspacing
\linespread{1.3}
\usepackage{url}
\usepackage{cite}

UPDATE: SOLVED{When I compile in TeXnic Center there is no error message, the only problem is that the output generated is the 2015/03/04 version. Yet no LaTeX file on this computer is from 2015/03/04, they're all up to date. I don't even understand where LaTeX gets this 2015/03/04 version from.
I've cleaned all the aux and log files with the "clean project" option then re-run TeXnic Center several times; but then TeXnic Center "couldn't find thefile.aux", it didn't generate a new one by itself. So I compiled the code written with TeXnic Center in TeXworks. It compiles fine for a bit, then ends with this message:
! File ended while scanning use of \emph .

\par
l.101 \input{ThesisIIA1}
Now again, TIME WARP: there was indeed an missing accolade with \emph in this file, but I corrected it and deleted all the files where the error was present. TeXworks doesn't seem to acknowledge this correction.
So I'm stuck with TeXnic Center that doesn't generate a new .aux file, and TeXworks that doesn't find the path to the corrected file… Please help!}

PS: both computers are running Windows 7. The old computer is dead. The new one is enabled to install packages on-the-fly. In case you wondered =)

UPDATE: after solving a code error it's compiling fine on Texworks now, but not at all anymore on TeXnic Center. Here's the latest lines on my log (I put [path] for the path): 

This is XeTeX, Version 3.1415926-2.5-0.9999.3 (MiKTeX 2.9) (preloaded format=xetex 2015.4.7)  8 APR 2015 11:11
entering extended mode
**Thesis.tex

("[path]\LaTeX\Thesis.tex"
! Undefined control sequence.
l.1 \documentclass
                  [a4paper,12pt]{book}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

! Undefined control sequence.
l.2 \usepackage
               {amsfonts}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

! Undefined control sequence.
l.3 \usepackage
               {amssymb}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

Same for each and every package… Packages that all were summoned just fine yesterday. Sigh. So the question now is: where do I check if all packages are called in properly by TeXnic Center?

Best Answer

Please do not edit the question to ask unrelated questions, it makes the site impossible to follow later, open a new question for new questions.

The original problem was exactly as indicated by TeX, a missing } meant that the argument for \emph{.... was not closed before the end of file.

The new problem is that LaTeX commands like \documentclass are not defined as you are using xetex (plain TeX) not xelatex (LaTeX).

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