Root problem in connecting to the internet via mobile network


i just bought a samsung galaxy ace plus a few days back... first three days i could connect to the internet via tata docomo(as i have unlimited internet plan) but after that for the last three days i can't open,mail,youtube,map, market,none are opening...i tried changing the settings manually ,'Use packet data' is also ticked ,have also gone for the 'reset factory settings' but nothing is working...always 'unable to connect server' is being shown. can anyone plzzz help me?what do i do?