I can provide specific troubleshooting steps or configuration files based on your needs.
If the standard "Wijesekara" layout is difficult, these tools allow you to type phonetically (e.g., typing "amman" to get "අම්මා"): Helakuru for Windows sinhala unicode for windows 8
Here’s an interesting and useful feature covering , which was a significant improvement over previous versions. sinhala unicode for windows 8
on how to install a specific phonetic keyboard like Helakuru or Keyman? sinhala unicode for windows 8
Comprehensive Guide to Installing and Using Sinhala Unicode on Windows 8