You need to edit the ID3 tags of the files. Changing the file names themselves won’t help. A great, free dedicated tag-editor is MP3Tag. The first thing you want to do is change the default Write setting to ID3v2.3 ISO-8859-1. This is the format that works best with Sansa players. Then you can edit the titles as needed to play numerically and correct any errors that may be present. Just remember to hit the SAVE icon when you’re through to save the changes.
Also note that it generally works better to make these changes to the file while it’s on your computer. Delete the ones on the player and transfer back the newly-edited files.
