As I understand it, from a simple Google search, WordPress - the software - will allow the use of any add-in software to play music files. A number of these will play only MP3/4 and such like, but some I understand will play midi files. One of these will in turn need to be linked to the midi mapper on your PC, I assume, to get at the sounds, I doubt that the application can do everything. The problem I assumed WAS that WordPress - the site/host - places restrictions on loading such add-ins. You'll need to find such a prog that does play midi files, and then set things up on your PC so that it can play. I assume you CAN play midi files not, directly, on your machine (i.e. NOT thru the web)?
And no, my website isn't hosted by wordpress. I use a diferrent one. So, is there a way to do it somehow? It is important for me to upload and play my midi files on my website. It doesn't have to be through wordpress. I have tries joomla but I didn't like the themes, so I switched back to wordpress.
If your website uses WordPress and it's hosted by WordPress then there seems to be a problem - according to a Google search. The WordPress hosting setup does allow certain (a VERY select) range of plugins for playing music, but the ones allowed, I understand, do NOT include ones that will play midi files.
If you really must play midi files, then you'll need to move the site to another host, or use a different system.