my power button does not work, unable to press the power button in the iwatch

You're missing the point; the off button itself on the phone is unpressable; it will force restart fine; the tiny power button will not turn the Apple Watch off. You have advice like the person is an idiot

This seems as an hardware issue to me. Please Contact - Official Apple Support to get support on this issue

You don't say what state your Apple Watch is right now (power on or off).

If the watch is powered up with the display alive, try a Forced Reset. Simply press and hold both the Digital Crown and the Side Button (together) for about 10-20 seconds until the white Apple logo appears, then release and let it reboot.

If the screen is dark and you think it is powered off, the battery might be discharged so put it to charge for an hour or so. Putting a (powered off) watch on charge should also force it to switch on so it can control the charging.

Also, on your iPhone look in Settings > Bluetooth to see if the watch shows as Connected (might suggest it is powered up but a failed display).

If these don't work then WheelieNick is probably correct, you have a hardware failure needing Apple's hands-on assistance.

You should learn the detail before answering.