If I understand you correctly you are saying the following:
- You reformatted your computer: in other words you have reinstalled Windows from scratch ?
- Now VC is not recognizing you very well. In other words, the confidence rating for recognition of a command is too low, or it does not understand you at all, but sometimes it works.
So it sounds like you have a problem with your sound. Something other than VoxCommando has changed. You need to look at your microphone settings. Maybe your volume is too high or other settings for you microphone have changed, or you changed the driver for your sound card.
Solutions:
It is probably not related but to be safe you should start by purging the cache in VoxCommando and then do a full restart of VC.
http://voxcommando.com/mediawiki/index.php?title=Main_Menu#Purge_CacheTest the quality of your microphone by using another program to record yourself talking and then play the audio file in order to make sure that your voice is being heard clearly. If the quality is poor and you cannot correct it by changing system settings, then you may need to get a better microphone. Built-in microphones on laptops are often (but not always) not very good for speech recognition.
Check your microphone volume is not too high, or too low. Bad quality recognition is usually caused by having the volume set too high.
Review the following tips:
http://voxcommando.com/mediawiki/index.php?title=FAQ#Why_doesn.27t_VC_understand_me_all_the_time.3FIf you are using the regular (non-SP) version of VoxCommando it is probably a good idea to perform voice training in Windows.
http://www.thewindowsclub.com/windows-speech-recognition-voice-training