Download a legacy Sinhala keyboard layout (e.g., "Wijesekara" or "Weweldeniya" mapping for Mi Nelum). Tools like KeyMan or Microsoft Keyboard Layout Creator can help.
Once you locate a Mi Nelum 98 Sinhala Font free download link, ensure the file name ends with .ttf (TrueType Font). The file size is typically between 50KB and 150KB. If it is an .exe file, do not run it—it is likely a virus.
Because this font is an abandonware (software no longer sold or supported by its original publisher), many websites offer it as freeware. However, you must be cautious.
If you only need the appearance for print, type your text in a Unicode font like "FM Abhaya," take a screenshot, or convert to outline in Illustrator. Then paste it over a Mi Nelum 98 background.