You can download
MIDI files from myxer.com, they offer almost any ringtone for free and if they don't have it you can upload your own song and create a ringtone. Save the file on your computer. Attach the file to an email and send email to your phone (depending on service provider, myxer should provide the email address to your phone, however myxer does not have the w755 listed as a phone, but I put the V3C as my phone and it still works).
After you receive the email on your phone, hit Options, go to Save Sound, hit Set As, then hit save as ringtone. Hope this works for you.