Display not detected - What else can I try?

So I read about setting display to Extend
I've tried updating the graphics card, looks ok and Device Mgr sez it's working
The external display, a TV, worked before on Win 7 just fine!

this is:
Win 10 64 bit Home was Win 7
HP Pavilion dv7 laptop
AMD Radeon HD 6300M Series video card
external display: large TV via HDMI

What else can I try?
thanks,
bill

Update: So I tried a 15 pin D on some other displays and it worked.
But the TV only has an HDMI input. So do you think an HDMI to 15p adapter would work?

Or does someone know how I can get the HDMI cable to work since it worked in Win 7?
I tried extend and updating the graphics card.

thanks,
bill
this is:
Win 10 64 bit Home was Win 7
HP Pavilion dv7 laptop
AMD Radeon HD 6300M Series video card
external display: large TV via HDMI