iPhone 3G touchscreen not responding!

My Iphone 3G touchscreen not working properly! My Iphone was in my pocket when raining and not completely soaked. The bottom half of touchscreen not responding when you "slide to unlock" or "enter passcode". The top half still works when you "slide to power off" and playing music. I left it for two weeks to dry out but still same problem and hoping there is another way to fix it before I try and open it up. I appreciate any suggestions that will help!