missing apps!

can someone plz help me, my friend tried to jailbreak my ipod touch 4g and something went wrong coz when it finished nearlly all the apps including settings, app store and safari are missing! all i have left are my games and some things that are useless to me (coz they're my sisters apps) and i found i can restore it to factory settings but i don't wanna loose all my game data and bought apps so plz can some1 halp me?!? 😟