Can anyone help? I've lost camera control

Apologies if this is the wrong place to post questions but I'm really stuck and wondered whether there was anyone on the forum who could help. I reduced my page size to access the word start button and when I reverted back to full screen I had no camera control. I've tried everything but can't seem to get it back. The only way I can navigate now is by using the Ctrl key but it takes longer so I really want my camera control back . Any advice would be appreciated, thanks for your help.

LOL Hope - seems to be an epidemic of this today. Here's the earlier thread .