RINGTONES DONT WORK! they seem to work on my sisters phone and not mine! HEEEEEEEEELP!

The signature works differently ,type the message and in the advanced options use the add signature to insert your signature.By adding your signature message will be send as picture message ie mms message not as text message.
You can find useful information at the following link
http://forums.wireless.att.com/t5/Sony-Ericsson/New-w580i-owner-with-some-questions/td-p/1555891

Your phone may not understand the mp3 format as a ringtone. Call sony and ask them for help... Let me know their response

I had this same phone and the same thing happened to me. I kept shutting it off and on - also taking the battery in and out. I eventually got the screen to light up but it would only last a few seconds. Sorry to say but you will most likely need a new phone. I had to replace mine.

go to the menu > my stuff > music > ringtones. that is where your ringtone program probably stored the ringtone that you created.

cheers.

the sim card probably fried or its probably the phone. thry upgrading to a new one
good luck

Try this.....
Sony Ericsson - Update Service - Update service software
Follow the instructions to install the USB Flash driver. ... W580i. W200i. K550i. W800i. K508i. K790i. K530i. W960i. P910i. K700i. W550i. Z520i. M600i. W660i ...
sonyericsson.com/cws/support/updateser...

hope it will fix the issue so dont forget to rate it...

Absolutely. Simply edit the contact and change the ringtone for that contact.

If you want to use custom ring-tones, you can create these on your phone. For MP3s, you may need to unlock the phone first.

look into you file folder for the ringtone it will be in there

take back the phone to where it was purchased and get a new one or have it serviced

camera is not working i mean that because of some soft ware problem my phones cames pictures is not saving when i take photo darait it comes menu