No response from the modem

hi i m a newbie to AT!!!

and my modem does not respond to any of the at commands im writing,
it dosnt even respond to get version or get information about target button in the target monitoring tool!!! there is a message that says “not dumping” at the botom right of the monioring interface,

could u plz tell me how i can reset the modem or install a fresh copy of firmware on the modem

thanks

JOGA