help please

hello everybody
i have iphone 4s 16G black 8.1.1 with jailbreak i downlaod a tweak from cydia ‘appsync’ after that the system is blocked i restar the iphone and it work’s but the probleme is i can’t downlaod the application from appstore 😮 and also i can’t upgread applications and whene i conect my iphone with itunes he can not detected. i delete all sources downlaolding but it’s stell the same probleme
i ask please if you have solution for this probleme without formatting my iphone i would like keep my informations
thank you very much