Timer Didnt Go Off

Sucks when a timer doesn't work doesn't it? I almost killed my mother plant due to a faulty timer.

At any rate, based on limited info, you should let your plants get 12 hours darkness before you switch again. My reasoning is that experiments have been done with extended light schedules on flowering plants (meaning 12+ hours light with 12 hours dark) with increased flower production but a much longer flowering time overall. To me this means that you can get away with extra light time during flowering but in order to stay in flowering you would need 12 hours of darkness.

To get back to your original time you could slowly increment your on/off times to approach the time you had it at originally. Switching back immediately may not hurt your plants either but if I were you I'd go the route I detailed.

Just fix the timer, stick it back on 12/12 and ignore it. one night is not gonna cause any real grief, just make sure it doesn't happen again. I had this issue once a week suing a £5 timer anbd a 400w HPS, i had to get on ebay and buy a timer with a built in contactor and it's all been peachy since.

Make sure the timer hasnt melted inside, and if it has, ur lookin at a fire risk. Contactor to be safe....