Changing tip on soldering iron

not getting as hot as it used to.

I loosened the screw on my iron and the tip came off.

If that didn't help you, you might be more descriptive. Which make/model/tip??

Plug the soldering iron into AC power and it will get warmer. You might also use an AC volts guesser to measure your AC power. Also, check the temperature with an IR thermometer.

Did you torque the nut that holds the iron?

There are exploded views of many soldering irons available on the web. We can help find them once you disclose the maker and model. If it's a cheap piece of junk from China, a photo might be helpful as many of those lack instructions or replacement parts. Also note that you can buy a cheap junk thermostatically controlled soldering iron from China for about the same cost as the probable replacement parts for your unspecified model iron (tip, heater, thermostat, lost screws, etc).

If the soldering tip is threaded, my guess(tm) is it's a Radio Shock soldering iron, made by Ungar: These have the irritating habit of corroding in place making removal difficult. I usually throw these away because if the tip is loose enough to be removed, it's also too loose to conduct the heat. These were replaced by a locking screw, which is marginally better. Something like this:

After you've destroyed your soldering iron trying to repair it, you might consider investing in a thermostatically controlled soldering iron, with easily replaceable tips, such as one of the Weller soldering stations.

not getting as hot as it used to.

sometimes it's retained by corrosion and friction after the fastenings are loosened

Is this a brand-name one or a cheap one?

it's not getting as hot as it used to.

it's not getting as hot as it used to.

I am glad that i knew better than to use my crystal ball on this request. The last time i tried to ask if for unknown make and model for an unknown poster it went totally cloudy and took a bunch of time and expensive advanced spell casting to repair.

If you can't be bothered to give us a fighting chance to help you why did you bother asking?

?-)