I have an HTC One M9, and unfortunately, the power button got broken. Therefore, I can no longer restart it. I tried holding the volume buttons while charging, options appear on the screen but I still have to use the home button to select one of the options. I do not know what should I do. Anyone can help, please?

Buy a new one and fix it

https://www.ebay.com/sch/i.html?_nkw=htc+one+power+button

Here's how,

https://www.youtube.com/watch?v=6PcEW4X2Wow

Or find a local phone fix it shop, and pay a guy for his knowledge, and know how, OR buy a new unit.

https://www.cheap-phones.com/?s=HTC+One+M9+for+Verizon&sa=search&scat=34?utm_source=bing&utm_medium=cpc&utm_term=htc%20one%20m9%20verizon&utm_campaign=bing

For what I would charge you, a new phone would be the way to go.