Serial programming issue after using ISP

I've been using the avr-mkII programmer to program the arduino through ISP for the past month. Recently I noticed that ever since doing that I lost the ability to program the arduino through the USB port - Serial 0. Does anyone have a clue as to how to reset the boards back to normal? I tried this with a few different boards and it is all the same. The New boards that haven't been programmed through the ISP act normally. I basically have lost the ability to communicate with the usb programmer chip. Has anyone experienced this before? Would I need to program the usb communication chip through it's ISP pins? Here the typical generic response that I get when I try to program them.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer

hamidsani:
I’ve been using the avr-mkII programmer to program the arduino through ISP for the past month. Recently I noticed that ever since doing that I lost the ability to program the arduino through the USB port - Serial 0. Does anyone have a clue as to how to reset the boards back to normal? I tried this with a few different boards and it is all the same. The New boards that haven’t been programmed through the ISP act normally. I basically have lost the ability to communicate with the usb programmer chip. Has anyone experienced this before? Would I need to program the usb communication chip through it’s ISP pins? Here the typical generic response that I get when I try to program them.

avrdude: stk500v2_ReceiveMessage(): timeout
avrdude: stk500v2_getsync(): timeout communicating with programmer

When you program via ISP, the bootloader is overwitten. To revert to serial programming, you need to burn the bootloader again.

Burn the bootloader. Programming with ISP or ICSP erases the bootloader which is needed for USB connections.

Awesome. Thank you guys. That did the trick