Dear Thorsten I apologise for not saying thank you earlier, I did not receive an email to notify of a reply.
Thank you for you reply. The issue was with K2 user module, when I clicked "my account" the option to add/change avatar was unavailable. When I create a Joomla user profile page, I can add/change an avatar and it then appears in the K2 profile and log ion module.
It is, I think, one of those strange anomolies that I will never understand, but I seem to have found a solution
THanks again for you reply