I have a wireless keyboard, and for some reason a few months ago it decided that left-control will shut off the keyboard. After going back to the game after a few months, I realize I can't really move the camera anymore without the mouse (I'm using S3 camera). Is there a way I can re-assign the keys so I can use another key to turn/tilt the camera instead?

I know I can just switch to default camera mode, but after 6 years of being used to S3's camera I can't get used to S4's

Haha I think I'm just gunna order a new keyboard, problem solved (not really but it still works XD)

You can't reassign keys, and I completely agree that you shouldn't have to inconvenience yourself with TS4's awful default camera controls.
I'd generally recommend against using wireless keyboards and mouses since they're not very reliable and, well, require annoying expensive batteries. Unless you absolutely have to use a wireless one, you'll be much better off with a regular keyboard, preferably one with nice clicky keys.

I've been using the same rechargable batteries in it for the past two years, it's been fine up until that most used, very useful key decided to go *pop* I'm an off switch now.

I'm hoping I'll be able to get my new keyboard before Pets releases.

Had the same problem when a few of my keys stopped working, unfortunately I also went the same path as you to fix the problem!