My Old Mac G5 doesn't shut down.

Hello guys! So I have a Power PC Mac G5, it means really old, I do have this machine about 10, 11 years, at least and never it gives me any problem, just some times the fan starts to run while I'm use it, but just once in a while. Okay, so now it doesn't shut down and take a several times for it, but it won't, for sure. I'm getting upset because of it and I get starting so nervous about this, so I have a lot of stuffs in there, movies, songs, pics, documents and whatever on it, but I have to buy the external hd, okay so forget about the external hd. I'm here to ask to solve this problem. Please, do you guys have any idea to solve it, shut down the machine, get it back to normal, this is happening because I was checking out a headphone with bluetooth, that's why this is happening. Please, do you guys have any idea to solve this problem, to shut down normally and get back the machine to normal again, I have important documents on it. If so, please, help me out.

Thanks a lot!