Here is the Guide!
(Download link VM)
1. Root your phone. (will void your warranty)
2. Download 'FX' (or any other Root Explorer app) from market.
3. Download 'DroidSansFallback.ttf.zip' attached file to your sd card.
5. Open fx explorer and locate your file,exract it, copy the font, go to /System/Fonts, then replace {backup this original file to sd card} already existing DroidSansFallback.ttf with the copied file. make sure you click on Lock Icon(in top right corner} before you paste font in fonts directory.
6. 'Permissions' should be rw-r-r.(to easily see this,change the view to list}
otherwise long click on copied file,select permissions.
7.exit the app.
8.immediately Reboot your phone and enjoy.
To write in Punjabi,
install Gurmukhi Keyboard from market.