I’ve been thinking a way I would address this issue in your place.
Since I do not know your installed system “Prepros3 Live Preview”, I have chosen a global approach.
I assume that you are working on a Windows PC (you named WAMP) as you computer.
Please really use Notepad++ (or Notepad++Portable), if it is given by me! It could be crucial to solve this issue.
Upload and save the following lines as file `testhtml5.html´ in the root of your server:
<html lang="en" dir="ltr">
<!--[if lt IE 9]>
<title>HTML5-Page in "UTF-8 without BOM"-Format</title>
<h1>HTML5-Page in "UTF-8 without BOM"-Format</h1>
<p>This line one is with "HTML named entities": ä ö ü ß Ä Ö Ü :end.</p>
<p>This line two is with "UTF-8 chars": ä ö ü ß Ä Ö Ü :end.</p>
Go to step 2.
Download the file to your PC using FTP and then examine the download in Notepad++ (or Notepad++Portable). If your server runs on your PC open it from there directly using Notepad++ (or Notepad++Portable, http://portableapps.com/apps/development/notepadpp_portable).
Are you sure, it is saved there in UTF-8 without BOM-format? Look at the Notepad++ status bar on the right (the fifth section) for “UTF-8 w/o BOM”!
If yes, go to step 3.
If no, correct this using Notepad++ (or Notepad++Portable) and go to step 1.
Open this file in your browser by accessing something like “http://127.0.0.1/testhtml5.html”.
It may be that you need to adjust “127.0.0.1” or need to supplement the port.
Do you see something like:
This line one is with "HTML named entities": ä ö ü ß Ä Ö Ü :end.
This line two is with "UTF-8 chars": ä ö ü ß Ä Ö Ü :end.
If totally yes, go to the last step.
Otherwise go to step 4.
Are you using an up-to-date browser version?
If no, install a newer browser, e.g. FirefoxPortable ( http://portableapps.com/apps/internet/firefox_portable/localization ), in the newest version. After that go to step 3.
If yes, go to step 5.
Your server configuration has a problem, where I unfortunately can not help you.
I would look at the help- or FAQ-pages from your server!
This issue has finished, when my simple page is displayed completely correct like in step 3. Then go to the next step.
Otherwise go to step 5.
Please give us a detailed description, what/where was the problem (located in which step?) and what you have changed.
After that you can close this issue, if you want.