Sharon in South Georgia:

I usually have a lot of success in finding operator’s manuals but only found one old ad for your MW. I did look up instructions for two different brands and found their instructions. If either are at all like yours maybe they will jog your memory or possibly even work for you.
1. Press and hold the Clear/Stop button for five seconds to lock the controls. Press and Hold the Clear/Stop button a second time for five seconds to unlock the controls.
2. To set (the Child Lock) touch CLOCK, the number 1 pad and then touch the START pad and hold for 3 seconds. Should a pad be touched, SA FE will appear in the display. To cancel, touch CLOCK, the number 1 and STOP/CLEAR pads. (Sharp brand)
Usually unfamiliar brands are manufactured by well known brands. It is more helpful to do a search with more information such as model number. The label with the Model and Serial numbers might have more info on the manufacture. Some times the additional information is helpful trying to search for such information. I presume you have unplugged the microwave in hope of resetting it. I will keep looking and checking back. Good luck!!