one of my speakers is loose

@kizuna22 all of this will depend on what make and model your headphones are. On most of those, you can remove the speaker by removing the earpads first. Then there could possibly be a few screws holding the speaker grill etc. to the shell. Once you have it apart, you can assess the damage. Hopefully the speaker just came "unglued"etc. You will know more once it is apart. This "without running the risk of damaging something" depends on the ease of working on your headset. Just like any other repair, take your time and do not force anything until you are sure you removed all the fasteners etc.

Ones it is parat, you can post some pictures of what you find, or if you are stuck with the disassembly, with your Question. that way we can see what you see and hopefully help you out further.

Adding images to an existing question

While you work on your headphones, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!