Laptop changed

Help, I'm new here, I have tried lots of solutions suggested online, but nothing seems to work.

We often use the HDMI lead to watch content on the tv.  Worked fine.
Latest time I went to use it , the screen would not transfer to the tv. Completely blank. Also at the same time, I noticed that the screen resolution had increased, and now I have lost the SLEEP function. It's as if something changed or updated without my knowledge.

Can anyone help me fathom out what is going on? I'm completely baffled.