Audio on some files in WMP is only squealing, interference noise

I am new to this so I apologize in advance if this isnt the correct section to put this is but I am just going to give as much detail as I can and hopefully someone can help

So when I have multiple video files playing in Windows Media Player 12 on my windows 7 hp mini I never had any issues for some reason I've noticed recently that only on certain files and its always the same files there will not be any audio but I do hear something that is hard to describe but it sounds like sound interference or a little like rewinding a cassette tape its pretty off putting and I cant figure out why this suddenly happened to these few select files now I am playing these files through my WMP library I set up so I dont knos if the problem is WMP or is it my speakers or is it the video files themselves only reason the video files isnt my pick is because I've seen every file in this folder play fine and never have a problem so I hope it is just some setting I accidentally turned on or off so please if anyone had this happen to them or just know a lot ill take whatever I can get and if anymore details needed please just ask im brand new so I apologize if anything is wrong but someone please give me some advice. Thank you

Right I have taken that into consideration I just wasn't sure if there was any other reason it would be happening I do have these files on my external hard drive so it is highly possible but is it possible that the Library I set up for WMP could of gotten basically corrupted