Midi file won't play

I apologize for the lack of clarity. They are ".mid" files. I understand what they are, I've been using them to create remixes of songs for a few weeks now. The program that is opening them is Quick Time Player. They have been opening and playing correctly up until today. If you didn't understand how they aren't working, its that I can't hear them. Normally they'll play with Quick Time Player, and I import them into Garageband and all that, but today there isn't any sound. I was able to take one off the internet and make a remix out of it with no problem. I'm just puzzled as to why I can't hear them at all. Thank you!

I apologize, I tried to explain that. I don't hear any sound at all out of them. And it's only with .mid files. Everything else works perfectly fine in quick time. Only .mid files are silent. But they were fine the day before and I haven't done anything that would change that. Any ideas?

I have not done that, I shall try now and let you know if it worked. Thank you!

Update: Unfortunately, those settings didn't help. Its not a midi keyboard I'm using, its just the type of files that won't produce sound. I didn't touch the audio midi setup app, and haven't done anything AT ALL to this computer. I cannot even think of why this is happening. I'm going to restart the computer again and see what happens. And if those settings actually will help, please tell me what to do in there. Thank you!

Haha I'm sorry, either I'm being extremely unclear or people aren't reading what I'm saying. I am downloading these .mid files. Here's the website if you want: http://www.ninsheetm.us/index.php. I am then clicking on the midi buttons shown on a page from that website, and then get to this page, for example: http://www.ninsheetm.us/sheets/Pokemon/PokemonBlackWhite/AccumulaTown.mid.

I get to that page so I can listen to them and sample them. This uses quick time player 7, which I have uninstalled and reinstalled to no avail. After I sample it, I then download it to my computer and am able to listen to it with Quick Time Player 7. If you go to the download page on apple's website for quick time player 7, the description says it supports the use of .mid files. You simply get an electric piano sound of the notes. I then import these .mid files to GarageBand and then use them to create remixes of the songs. It just frustrates me that the files were producing sound in quick time player 7 just the day before and randomly stopped playing for seemingly no reason. I apoligoze for sounding frustrated, but it seems only the first person who posted actually read what I said at all. Thank you for helping!

I'm baffled as well! Could you explain that new user techinque to me? I've been trying everything in settings.

Yes, I don't know if my posts look different to you or something, but I had originally put ".midi" in one post but then changed it to the correct type of file ".mid". Either way, fane_j is right, its treated the same so it doesn't matter. And the link worked? then it must be my computers and not the application. Thanks for the input!

Thank you! I'll try that out and let you know what happens.