Black screen soon as desktop shows

[gaz1971uk]

Using a pi3, has been running ok for 6 months, screen went black, thought it was cable cause I’m using a vga to hdmi connector, but I’ve tried different screen and just a hdmi cable. What’s confusing is that the mirror is still working as I’m using the remote module and I can view it on my laptop, the screen is ok cause it’s going through the boot , just when desktop shows it’s goes off