H1B Transfer after leaving sponsored company from India

[basavesht]

Hello,

I've a valid H1B visa sponsored by Company A. I didn't travel to US even once and have also left Company A for some reasons, which has sponsored my visa. I have all the documents (petition etc) along with stamped visa with me.
Currently am working with a Company B in India. Now, company B is not ready to get my visa transferred because of there few internal restrictions.
My questions are
a) Does my visa still holds valid for any other employer (say Company C) having presence in US to get it transferred ?
b) If yes, is it possible to get an H1B transferred while I am still in India?

Please help ....

Thank you