Help cant load new programs and sketches

I'm very new to this whole skill set. I'm currently taking a class on using micro-controllers and today in class I was experimenting with the Loop sketch and I was messing around with the formulas. At first I changed the "For i=0 then..." formula before the Loop and changed it to "a=1.." and so on. Then I plugged it into the Loop sequence and changed i's to a's then I uploaded the program. It loaded and the sequence went through LEDs in the bread board once and stopped. All the wiring was right so I can't imagine I fried the board,but the program is still on the board and its on the fritz. Does anyone know how I can delete the program/sketch off my new Arduino or how I can reset it to allow for a new program to be put on it. I might have pulled the Arduino out of the USB cable jack when I was trying to upload a new program after I saw this one glitch up, only because the computer and the program seemed to have froze up. Back to top

its on the fritz

Can you tell us the exact error messages that you get, if any?