CV joint and axle, I may have separated the inner joint?

There's a set of three rollers in there that spin on needle bearings. On some designs, those rollers will fall off their shafts and the needle bearings will fall out. To address that, you'll need to remove the entire half shaft and the large end of the boot, then put the rollers back together.

On other designs, the rollers will not fall off, so you can just stick the joint back together.

There are also differences in the design as to how the rollers are held in place. Very few will allow them to just be pulled out along with stretching the boot. Some have a stiff wire ring that must be pried out to let the rollers come all the way out. Others have a thick formed metal plate with ears that must be bent to open the way for the rollers to come out. On still others, the rollers can be removed one at a time by angling the shaft in relation to the inner joint housing further than it can go while it's installed on the car.

Where I would start is by undoing whatever you had to do to get the joint to come apart. If you're lucky, the rollers are trapped in place on the shaft and they'll go right back in. There's a spring in there that will need to be compressed, so expect to need to use some pressure to push the joint back together.

If you're able to get the joint back together, first try to rotate it forward and backward. There must be no play between the shaft and the housing. If there is, at least one of the rollers fell off. Next, squeeze the boot in various places to see if you can feel any parts moving around. The rollers are roughly 1 1/2" in diameter and about 3/4" thick. You won't be able to feel the needle bearings.

If you can't push the shaft far enough into the housing to allow the outer joint to be installed in the wheel bearing, chances are the spring in the inner joint fell over. You'll need to remove the assembly and take the inner joint apart to fix that. If the spring is still in place, you can push the shaft into the housing about two inches, then it will pop back out under that spring pressure. If you don't feel that pressure, the joint must be taken apart to reposition the spring. You'll need both hands to push against that spring.

Working with these joints can be handled by a competent do-it-yourselfer, but it's a very messy job. If you're having other problems, such as clicking when turning and backing up, or a boot that has been torn for some time, you might consider just replacing the entire half shaft. New ones today are so inexpensive, it doesn't pay to get a used one from a salvage yard.

This drawing shows the exploded view of the half shaft. Items 1 through 9 are the inner joint. They don't show the spring I mentioned. My red arrow is pointing to where it is.