That thing is 14 years old, in tech terms, that's prehistoric. Whilst there are online stores which sell cables (which you could have found if you'd bothered to a) search this forum and/or b) searched the Web), I really don't know what you propose to do with it as a) there have been no drivers released for it since XP b) Sony Connect Music was killed off in 2008 and c) it requires a computer with USB A ports.
The cable you need is a 30-pin USB A cable, If you search for 'NW A-3000 USB cable' you'll find a company called Suntek selling one for around £11 (of course you might not be in the UK, but I am, so that's what you're being told).
But, really, you should think about replacing it. Yes, I'm grumpy this morning.
