commenting on other blogs

Hello, I have been using my wordpress.org website for ten years now. Previously when I left a comment on someone else’s blog, be it wordpress, blogger or whatever a link back to my site was always present. Two years ago or maybe a little more this changed and so many times whilst making the comment I am now asked to login. More often than not I am logged in to my dashboard anyway. However I have a go at logging in to wordpress.com or my gravator only to get a message which says this is not your site or some other similar untrue message. I have tried for two years to get this resolved through .com or.org Please I really want this resolved can someone take the time to help me out with this
Alistair http://www.aberdeengardening.co.uk/diary/http://www.aberdeengardening.co.uk/diary/