Keyboard and power on off button doesn't work.

@yogeshprajapti sounds like the keyboard failure has now extended to the power button's internal circuitry, preventing the laptop from turning on.

Remove the lower case. Unscrew all fasteners on the bottom panel and use a plastic prying tool or card to carefully release the clips around the edges. Next, disconnect the internal battery. Locate the cable that connects the main battery to the motherboard. Gently pull the connector straight out of its socket to disconnect it. Leave it unplugged. Now, reseat the keyboard cable. Lift the plastic locking flap on the connector, slide the cable out, and reinsert it completely to rule out a loose connection. Press the flap back down to lock it. Next, try to bypass the power button. While the internal battery is still completely disconnected, open the laptop screen and plug your AC adapter into the wall, then into the laptop. Connecting AC power while the battery is disconnected should force the motherboard to boot automatically. If the system successfully boots into Windows, carefully reconnect the internal battery to the motherboard and reinstall the bottom cover. If the laptop remains completely unresponsive, the complete keyboard palmrest assembly must be replaced to restore power functionality. To work on it, use the guides from here Acer Aspire 3 A315-58-350L and videos like this (slightly different model but same idea) to augment those guides.