After finishing A Blade in the Dark quest, I came across a dragon nest with a Dragon flying around it, and after I killed it... I didn't absorb its soul... Now I havn't seen a random dragon Spawn since... Is this a bug or what? and is there a way to fix it by chance?

This is two seperate points your erronously putting together.

First, blade in the dark; At this point in the MQ you dont get random encounters by design. Delphine tells you exactly where the next attack is, so therefor they cant be anywhere else. Once this quest is done, you have to move it on to the initial part of the next part of the MQ ~ diplomatic immunity, before random dragon encounters occur again and it may take some time to do so.

Secondly, dragon souls; When killing a dragon at a word wall site, respawned dragons will not give souls. However if the respawn dragon is a higher level version it WILL give a soul. So for example if you killed a "Dragon" and it respawns as "Dragon" again it wont give a soul. But if you killed a "Dragon" and it later respawns as "Blood Dragon" or similar it WILL give a soul. Only when the respawned dragon is of a higher version will a new soul be granted.

Try to fast travel around a lot, dragons are more likely to spawn after fast travelling (especially to Dawnstar and Morthal etc).

Are you sure? I've always got dragon souls from any dragon, regardless of my level and the dragon's level...

Yes, it was confirmed a while back. And a bug was corrected in a prior patch to allow higher level soul capture iirc. Generally you dont normally meet similar level respawns because you advance the character enough that the dragons move up a grade so you always get a soul at a world wall site.

Thank you for your adivce... I read some other pages, and they said to check the consol... I typed GetGlobalValue dragonsenabled... and they said it should come back dragonsenabled 1.00... Mine said 0.... So I typed Set dragonsenabled to 1... and that changed it back to dragonsenabled 1.00...

Should I change it back to 0? and the dragon I killed was a blood dragon, and at a dragon mound i hadn't been before, I got the word of power.

I never advise using the console for any reason. Its far to easy to completely kill a game save that way. I have no idea what those commands do or how it affects the game so I cant give any advice on how to proceed that way, sorry.

As for the Dragon, a few word wall dragons actually move around the game world in the vicinity of the wall. So if you have been anywhere near it and killed a blood dragon, chances are it was the word wall one. Its very easy to note this with the dragon site to the south of Windhelm. That dragon never actually stays on the ground, its always flying around the area.

Well.... The Set dragonsenabled to 1 seems to have done the trick... They are spawning now.... after afew fast travles the dragons are showing up, and I take their souls.. Its weird that it got turned off.....

I am at the stage where I am suppode to meet the blade women at solitude stables... and it still read dragonsenabled 0..... I have multipul saves.... and it doesn't seem to be turning back on without me enabling it....

I ran into a no soul dragon that I had already killed once at the elder gleam cave which would never give a soul no matter how many times I reloaded and killed it, I downloaded the Unofficial Skyrim Update mod and loaded the same save game and the dragon gave me the soul, from then until I killed Alduin I never had another dragon kill without a soul. I can't honestly say the mod cured the problem but it was some coincidence that it worked first time after installing it.

I don't know if the higher level dragon explanation is correct or not, and I'm in no way calling you a liar Lexandro, but I can say that after downloading the mod above I never had trouble with any dragon souls. If you want to try the Unofficial Skyrim Update and have the 1.6 Bethesda patch installed make sure you download the 1.05b or 1.05c beta for it, the 1.05a version has dialog changes that 1.6 is incompatible with.