Copying MP3 files to device

I am trying to copy 30 mp3 files from my pc to a mp3 player. While I managed to put their # from 1 to 30 on my pc, once I copied to the MicroSD card, the numbers got mess up. the number that I pressed does not call up the track that I expect. Can someone help me? Thanks!

You need to find out what the player reads (just the filename or really the metadata?), which tag versions it understands (v1, v2.3, v2.4?)
Which tag fields are filled besides the track number (which I hope is what you mean when you wrote

oh wow, may i know how to find out what the player reads?

Well, you could modify a filename and see where it appears in the list.
And you could do the same with the metadata in a file. Like adding all the usual tag fields ALBUMARTIST, ARTIST, ALBUM, TITLE, TRACK
and then check again.

thanks for your advice

there is one thing very strange. When I added tracks to all the 30 files, the track number stays when I copied the files to a microSD card. But after I eject it, the track numbers are gone.

You eject the card from the PC card reader and the track numbers are gone?
This does not make sense.
It would now be helpful if you could tell us how you added track numbers to the files' metadata.
Then, a screenshot of the extended tags would be nice (Alt-t) or alternatively of the MP3tag files list with as many columns visible as possible.

I had the files tracked from 1 to 28.

then I moved the files by MP3Tag to my usb drive.

i checked the usb drive under windows explorer,

4 of the files that had track number 21 to 24 had their track number erased. I haven't even ejected the USB yet.

The thing is, I added files to MP3tag, then I use auto numbering to add track numbers. but the track numbers doesn't seem to stay with everyfile when I copied to other media, USB or microSD

Now we are getting on: this means there are some files that behave in a strange way.
I would suggest that you check the files with the utilities linked in this thread: