I'm unable to add a new address. I was asked to resolve or confirm my address and I now have a limited PayPal account. But my old address is no longer valid, and I am not able to add a new address. What do you suggest?
You need to contact customer services to resolve any account specific issues. Click help / contact bottom left of Paypal pages for options available for your country.
Or have you considered contacting Customer Service via Facebook or Twitter? You can send them a personal message from their facebook or twitter pages. It's: https://www.facebook.com/PayPal and @AskPayPal for Twitter.
Advice is voluntary. Kudos / Solution appreciated.