really odd buyer

[OnlyWantsOne]

I sold some tops (3 tops) they paid promptly, I sent the item - marked it as dispatched, heard nothing from buyer to say had recieved it - any way, the parcel has now been returned to me (via collection depo - says not known at this address on parcel)

have contacted buyer, and asked if everything ok, they havent got back to me? what do i do?

They've probably forgotten to change the address on their Paypal account.
Give them a couple of days. Probably snowed in somewhere and cant get home to check emails.

If it is that they have forgotten to change their address, at least they have been returned to you. I had a nightmare once where someone hadn't updated their address and they got very abusive.
Anyhoo, I would contact them again tomorrow, and then on Saturday. I would leave it two weeks personally (in of them being on holiday) before refunding and relisting.

You pull their contact details and ring them. Did you send to the address on the PayPal transaction page?