Replace LInes of text with a keyword

[bjotorres]

I need to select and replace lines of text in the middle of a file with one keyword. Does anyone have code for that?

[roxer]

hi, bjotorres
Can you specify more clearly your task: you should find text line which contains keyword and replace this line with other text, OR you need to replace particular text line (and you know number of this line) by keyword (so this text line will contain only keyword)?