Hi,
Have a peggy2. Uploading from arduino dev environment worked well at first, then started to have difficulty uploading. Had a program in there which didn't turn on LEDs, but reported values to serial port.

When it wouldn't upload, it would still report values to the serial port (all the while, leds flashing in random fashion, as the DDRs weren't defined for the ports, I assume...

finally, it stopped illuminating the LEDs or outputting serial, or accepting code.

suggestions?

There are a few different things that could be going on, so it's a little hard to be sure exactly what the issue is.

First, are you running on batteries? If so, could well be that you just need a new set.

Next: If not batteries, a flaky solder joint somewhere on your board is a likely culprit. Carefully examine all of the solder joints in the lower "CPU" area of the board and near the connectors. If you can find any solder joints that look flaky, dry, incomplete, or cracked, that might explain the trouble.

Is the board configured in the "serial" mode?