You can have many projects... Can you elaborate on what actually happens when you say you "can't connect"? Are you getting any error messages etc..?

Yes. When I want to connect my second site to the community space to browse add-ons, it asks me to log in, and then tells me it doesn't recognize the site and I need to reconnect to the community. When I log into the community, it lists my other site as a project, but there is no option to add a second project.
I am trying to get spanishmustangs.org.uk reconnected.

Hmmm... not sure why that would be... Are you logging in with the correct account? Do you have more than one account? You need your concrete5.org login details to connect a site to the community (not your admin login details for the web site).

I could try and have a look if you send me some login details but then your c5 community details are something you'd want to keep private.

Alternatively, here are a couple of resources that may be of help- http://www.concrete5.org/documentation/how-tos/editors/cant-connect...

http://www.concrete5.org/documentation/how-tos/editors/project-owne...

http://www.concrete5.org/documentation/how-tos/editors/reconnect-to...

Hope that helps; let me know how you get on.