My ipod wont sync to my computer or itunes but it will still charge? help

SO my ipod stopped syncing to my itunes for 2 weeks, the IPOD icon does not appear on my itunes screen to show it has sync also if i go to my "computers" to see devices that have been plugged in to my computer my ipod does not show up why?

EXTRA HELP !

I even have trouble with my email on my ipod the icon is blank now , doesnt show alerts and if clicked settings , mail ; then it says accounts are currently syncing . but clearly they are not.

another problem is my camera doesnt save my pictures that i take anymore, if there are taken before it can be saved on the ipod the ipod swiches to the home scrren.

my other problem is with some of my apps for example candy mania and jewel mania both have level setups like candy crush . i have completed many lvls previous to the glich on my ipod but now the higher lvls are no longer accessable instead they show a adownloading bar that never moves .

WHAT SHOULD I DO