Lay My Hat

On my laptop I was writing an email in Gmail when suddenly I found I wasn't writing anything!

Thought I could write this on my laptop but no the cursor doesn't move. Can't write anything anywhere on the laptop.
What have I inadvertently pressed and what must I press to be able to write again?

What model/make laptop is it? There will be a key you can press as you must have disabled the mouse if you haven't got a cursor anywhere.

Possibly control + F5 might work having had a quick google?

It's a Toshiba, Nemo. Should have waited to ask for help, as I re-booted and it worked again (I had the cursor but it just didn't move....)