Picasa.
 

I downloaded some photos yesterday (13-06-2013)from my camera (Lumix G5) and edited them successfully on Picasa, today I took more photos put them on my computer tried to edit them on but they wouldn't show up on Picasa, I then took some test shots put them on my computer, no luck with those either. It seems not to be accepting after 13-06-2013, any ideas in laymans language please.

I don't know the details of the Lumix, but all I can think of is that you my have changed a setting and be taking in RAW or some other format that Picasa doesn't recognise.

It seems you are not alone ;-) A response from Picasa can be seen here

https://support.google.com/picasa/answer/32690?hl=en-GB

Graham