H1B to H4 and then again H4 to H1B

I am holding valid H1b visa for next two years. Now I have to go on H4 visa for some reasons. My question is after sometime if I need to change my status again from H4 to H1B, what should be the process? My current employer can cancel my petition ?

MVerma : Did you ever get any response(s) to your question? Thanks.