Have you been removing suckers? If the plant's at all normal, sooner or later it will produce more suckers. Simply let one or more of them grow and you'll have a new main stem.

I was brought up to remove suckers -- pruning to one main stem -- but I soon realized I'd have more fruit if I let at least a few suckers grow (and the plant would probably be a bit shorter, which is a consideration for someone who's 5'2").

Some people believe suckers are evil/don't bear fruit/etc., but that's not true. Suckers are simply the tomato's way of growing branches.

In case you're worried about not having suckers because you already removed the suckers, eventually the plant will send out more suckers at the same locations where you removed the first suckers. Tomatoes have a very strong will to survive.

I have removed the suckers but they were tiny when I removed them.

There is some new growth that just started where it looks like the main stem broke off. Hopefully it will be ok. My other plants look great!

Should I be concerned with the leaves curling up?

"Should I be concerned with the leaves curling up?"

Well, it looks like tomato leaf roll, which most of the time happens in response to some sort of stress. In this case, I'd guess the stress to be excessive pruning or the loss of the central stem. Generally it's nothing to worry about, but I'd lay off the pruning for a bit.

My indeterminate is throwing out what looks to be many "main stems." How to prune? I've taken off all suckers ( as you can see one attempt removed the branch tip unfortunately). I'm using a trellis system this year but haven't yet tied up the main stem. should I tie up 3 or 4 ? This is my first year with the trellis! Thanks

It's difficult to tell what's going on there, dobieone, what with the mulch and the photo being upside-down.

But regardless, if this is a determinate, it shouldn't be pruned at all. Since I almost never grow determinates and cannot explain their growth pattern well, I will let someone else explain why.

Only indeterminates should be pruned (and only if there is a serious lack of space).