How can I use a private key to spend Ether and ERC-20 tokens?

I have lost my laptop which had a Terminal on it containint swarm city tokens (SWT). I still have the public address and the private key so can see on that the ETH and SWT are still there. However, I don't know how to use the private key to access the ETH and SWT. I have been to and but can't see how to do it from there. I was going to try and generate a new wallet, hoping it would ask me for a private key but could not get far enough – recommended downloading their desktop app – which I did and got a strange looking "" which I have no idea how to use – I am not a tech-savy person (though I am running Linux-Ubuntu 16 LTS). I should be most grateful for any help, bearing in mind that I am 69 years old and a bit dim (LoL!). Thanking you in anticipation, DB

Submitted November 26, 2018 at 01:49AM }
via reddit