Hello - I have had JA Contentslider working fine with K2 with frontend editing loaded. But suddenly the frontend editing is not working it just gives a blank screen when you click on edit. I have updated all the relevant components but nothing has changed. Please can someone advise what can be done.

Try enabling the error reporting through your global configuration to check if you get a specific error when you get the blank page.

This is the error I got - do you have any suggestions please.

Fatal error: Cannot redeclare class JSMinException in /home2/autotecg/public_html/plugins/system/jat3/jat3/core/libs/jsmin.php on line 377

This seems to be a conflict error with the T3 Framework.
Maybe this post from their forum would help you.

www.joomlart.com/forums/showthread.php?68714-Fatal-error-Cannot-redeclare-class-JSMinException-T3-Framework