Can't flash new rom!

[Rafy0003]

Back in Juky I flashed to the "new" Htc rom with sprint tv included, and after that my active sync was no longer working, it was working before that just fine and now I want to flash a new rom but don't have the connection to active sync to get the damn thing running. thus my question is: Is there a way to flash a new rom via sd card I've tried to do this several times but have always had some b.s. error come up. Can anyone help me flashing or getting active sync to work. Ive tried unchecking and checking everything tried diff cables, usb ports. diff comp. still nothing I have read on the isext.dd thing but got thrown off on that. Sorry for the long post.