Well, Windows XP and higher have an option to sort filenames either as 1,2,11,12 or as 1,11,12,2. Older versions of Windows didn't. And your mp3-player doesn't either probably.
So we do the old trick: number 01,02,11,12 and all's fine.
I can't help you with the deleting problem.
Hello, I'm having a couple of problems with my Christmas present (An MP815-4G MP3 Player.) When I was uploading songs I noticed that they weren't coming in the correct order that the CD is on. Although the properties had all the songs tracks numbered. So I started numbering all of the songs, example: D12 1 Another Public Service Announcement (That's the only one I can remember at the moment.), and when I turned my MP3 Player back on and looked at the music it did something I wasn't expecting. It did go alphabetically but did so, in numbers! example: 1, 11, 12, 13, etc. (I thought electronics were smarter than this.) So I need help with that there and another thing. I deleted a few songs off of my MP3 player while I was attempting to make the songs alphabetical. (Yeah, I'm spontaneous. By the way, is alphabetical the right word?) When I looked back I saw that the song was indeed gone but the album wasn't so I clicked on it. I found that the song that was on that album had been disguised and replaced by another song that was on a completely different album. I can't delete it because it isn't on my computer and I just can't go on explorer on the MP3 to do it because it show me the albums, only the songs. So what am I to do? I don't think deleting the song is going to work because it'll also be deleted on the correct album too and the non-existing album will just take another song in it's place. So if you have an idea I haven't thought of please give it to me.