If a seedling and not a grafted selection should be possible to grow new tree from basal sprout. May not need any help from you to grow erect trunk with new sprout. If in the open (full sun) new shoot may replace old, bent one satisfactorily. If you get several new sprouts from the base you might let it grow into a clump, if you like, otherwise let them grow for awhile and the select the one that appears to be largest and strongest, prune out the rest.

ok now the stump is still there ,and this sprout is growing off the stump but from underground, just to the left of the stump. will this be a tree alwasy growing off the stump or will it eventually thicken and have it's own roots? i mean do i ever prune away the stump

You needn't worry about the stump. After the tree has grown some, it will grow around and over the area where the stump was. Provided the stump is cut as low as possible, that is. If not, do this now, obviously taking care to not cut the new sprout.

+oM

This shoot should grow up to be a tree all on its own. If there are no sprouts coming from the stump, then you can cut the stump out. If there are any sprouts from the stump or from the rest of the roots, you need to decide if you want a multi-trunked clump of birch, and also if you want to grow a shoot from the stump. If they look like they would be attractive, let any additional sprouts grow - you can always take them out later. However, this is your tree, so if you don't like it, remove the sprouts and have just the one sprout.

I planted a grouping of 3 'Heritage' River birch seedlings about 6 years ago, and then, after 18 months, realized that the clump was far too close to the edge of the porch. I dug them up, and moved them further away. I had to leave one large section of root - it broke, and it was under a bunch of flowering bulbs. That summer, I got 5-6 sprouts off the root, which I dug the following year, in the fall, before the bulbs were above-ground or even growing, and planted as 2 clumps. All are doing well now.

Birches are tough, and really WANT to grow. You should water the new tree if the soil gets really dry, but since it is growing from a (hopefully) extensive root system, you don't have to treat it as a newly planted tree.

Since new growth is supported by energy stored in stems and roots, I wouldn't be in a hurry to cut out what is left of the old trunk. Just do it before it gets in the way of the thickening new trunk(s).

the lil sprout thing kind of leans to one side, since it's growing up out of the base of the stump. is that ok?

As it grows, it should straighten up. If it is still leaning a lot in a month or two, then you can drive in a sturdy cane next to it and gently straighten it, tieing it to the cane with something fairly wide and soft - old panty-hose are great for this. If it is still leaning a lot, then tie it in stages, so you don't break it - tightening up the supporting ties gradually over a couple of weeks. Check the ties periodically, and loosen them as needed, so they don't constrict the girth of the shoot as it grows. You should be able to take them off by fall, certainly by next spring.

Dibbits' method for if you do need to stake is sound. However, I strongly doubt it will be necessary. good luck!

+oM