what to do when your power button its dented its and it wont work

I'm afraid that you will not be happy with the answers.

Make an appointment at the Apple Store or take the phone to an authorized service shop in your area to discuss your options. They will likely tell you that the phone needs to be replaced.

You can find a list of authorized locations in your area by using the link below:

Find Locations

Don't want to guess and be wrong, but worst case you would be looking at the cost of a new phone, which will vary by model and features. Hopefully, there are other options to look at.....like a "refurbished" phone.