Open Microsoft Word or Notepad. Change the font dropdown to "Kruti Tamil 100". Type using a Tamil phonetic keyboard or the specific Kruti key map (usually: k for க, ; for ங, etc.).
The file is corrupted, or the font is not installed. Re-download and restart your PC. Kruti Tamil 100 Font Free Download
For the purpose of this article, we will assume "Kruti Tamil 100" refers to a used in older Tamil publishing. Open Microsoft Word or Notepad