Yeah, your guess is absolutely correct, frequent thunderstorms caused multiple times of electricity-out, and previously it also had initramfs error, which I had fixed, then recently the LAN got disappeared.
All in a sudden the LAN connection disappeared from my linux mint in last 2 days. But before that I used to browse smoothly, now the "pppoeconf" command doesn't show Ethernet card, and the "lshw" also doesn't show the network section. Please help if anyone knows about it.