I have a notepad having some number stored in it . How to get the row count for that notepad.

TestComplete provides below option,

def Test():
  fileName = "D:\\Files\\MyFile.txt"
  fileObj = aqFile.OpenTextFile(fileName, aqFile.faRead, aqFile.ctANSI)
  Log.Message(fileObj.LinesCount)
  fileObj.Close()

Ref : https://support.smartbear.com/testcomplete/docs/reference/program-objects/aqtextfile/linescount.html#description