Need help with iphone 4 charging!!

[youngn]

I have an iphone for, had it for over a year now and all of a sudden it stopped charging. I connected it to the mains charger, still no charge, connected it to three different usb chargers still no charge. I then switched the phone off and connected the phone to the mains charger, it switched on and when it came to the home screen theere was no charging icon - the little thunderbolt. Did the same with the usb lead it just switched the phone on but doesnt charge. And i have been using these leads and my mains charger for a year so they are compatible. Please can someone help me asap as i need my phone for work tomorrow. Thank You