The problem was that Java could not be reinstalled because the uninstalling process was not clean so that Java files were still in the registry, made the Java installer thought that Java was already installed.
We have download like ten registry cleaner software, tried 3 or 4 of them but the problem remained. Until we find a very useful ilnk that finally made the installation work.
The trick is to type <pre><code>regedit</code/</pre> on Windows start menu and then find any folder contains Java on the folder under <pre><code>HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\INSTALLER\PRODUCTS</code></pre>. This is a bit tedious but it is totally worth it 😀
After that delete these to folder:
<pre><code>HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment</code></pre>
<pre><code>HKEY_LOCAL_MACHINE\SOFTWARE\wow6432node\JavaSoft\Java Runtime Environment</code></pre>
and then all will be set and the installation will be done just fine.