Stock / original exhaust systems dont tend to last that long in my experience. Only real way to fix it properly would be to get it welded. Either that, or if your link pipe is still intact and it's just the end bit (Muffler) that fell off, get an after-market slip on muffler / silencer and slide it onto the end of the link pipe and clamp it down. Just find out the outer diameter of the link pipe, right at the end, then you'll know what inner diameter slip on you'll need.

Welding

sure, just try and weld it on for now, then you could cut it off when you get a new one

JB weld

Basically, while riding one day (2011 Honda CBR250R) my muffler just snapped off, but i was able to find it. Unfortunately it is pretty dinged up and some parts are cracked/bent. I attached three pics of the damage, and was wondering if i could possibly reattach it in anyway until i get a new one? The bolt to mount it is bent, the pipe a little cracked, and the other picture is where it snapped i guess, because it was connecting my exhaust pipe and it together