Q1. Is NetChecker free?
Ans. Yes NetChecker is completely free. You can freely use, share, adapt NetChecker. NetChecker is available under Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.

Q2. Why is there no GUI?
Ans. Command line is the best place to solve system problems. No GUI means no extra overhead, No extra load on system, no confusing menus. Navigation in text based softwares is more fluid than their counterparts with graphical interface. Beside that using text based software makes you look like a geek ;-)
I suggest you to read this wikipedia article,
Benefits of text-based software

Q3. Can NetChecker repair Mobile internet connection problems?
Ans. No. It can't! And due to technical difficulties it is practically impossible to implement this feature.

Q4. What versions of Windows does NetChecker support?
Ans. NetChecker should work fine on the Windows XP, Vista, 7, 8 as long as the locale of Windows shell is English. NetChecker's functionality is built around running and parsing data from Windows shell commands and utilities. And Since Windows shell is localized NetChecker won't work on Windows with Non-English locale. If you are running Windows with Non-English locale and Still want to run NetChecker you can use a tool called 'Englishize Cmd'. 'Englishize Cmd' can let you toggle between English and Non-English mode for most Windows shell commands. 'Englishize Cmd' doesn't work on Windows XP. It works on Windows Vista and higher.
You can get it from the following link,
Englishize Cmd

Q5. Question i have in my mind is not listed here?
Ans. Feel free to Contact me if you have any question regarding Netchecker.