ipod touch not recognized on itunes

hi everyone ,sorry if its the wrong thread but im kind a desperate by now..i ve been having this issue with my ipod touvh last generation,is like everytime i plug it it doesnt appear on i tunes.i try and called to apple help line and they made remove and install again itunes,reset the ipod and then restore it,well and this seems to work until next time i unplug and then try to plug it to put some more data in it,it doesnt appear anylonger.i tried everything,i put the songs i have on ipo first on itunes library,everything b,i just dont have it synchronised cause i like to do it by hand.can anyone please help,is that everytime i want to plug mu ipod in i have to reset it and uninstall itunes than instal it again,then restore ipod,everytime this drag,pleaaaaase help im desperate here now,i used to trust on apple but now....