Currently there is no provision to draw 'Underline' below typed 'Text' in Inkscape Version 0.48. Drawing underline for Text is normally required in daily usage. So kindly request you to provide me the solution to for the problem. Please help me by mentioning the required changes in code.

Oh gosh -- as a user/self help forum, not many of us would know how to change the code.

I agree that underlined text is a much needed feature, and I would not be suprised if it's already been officially requested [.....goes to search LP....]

Yes! a few requests

This is the most promising: https://bugs.launchpad.net/inkscape/+bug/1269206 A patch means that there might be a development version with this ability. Although I did not read the entire thing, so I don't know what the current state is.

Aside from that, I would suggest posting in the Inkscape User mailing list. Many developers participate there, and it's the best way to contact them. https://inkscape.org/en/community/mailing-lists/ (Or there's a IRC channel https://inkscape.org/en/community/mailing-lists/)