Each char in this game can learn up to 2 sub-classes (sorry, I do not know how it was called, but I mean something like blood mage for mages or berserker for fighters). You have to unlock them in the game (reading a skill book or learning it from somebody), but once you have unlocked them you can use them at once in every later playthrough.

I have finished this game a long time ago as mage and there I have unlocked all classes. Next time I want to play as rogue. In order to unlock blood magic, you have to be a mage yourself. I think all other classes can be unlocked by any char.

Is there a way to unlock all classes without playing large parts of the game with a mage?
The game is so large that even finishing it with one char takes a long time.
Since I have already finished the game as mage I want to play as another char.

I do not have the old computer anymore (where I have played the game) and I do not have an old save.

Im pretty sure aside from mods, you can't really unlock other classes advanced specs. Like for instance, i recall you can only unlock blood mage by doing a mage specific quest, that wont occur for other classes or party members.

Not true.
I've never played as anything but a mage and gotten all of them for all classes. If you go through the companion dialogues, you unlock several. I think blood mage MIGHT require a mage, but you can always buy the tome in Awakening and it'll carry over to Origins.

the classes unlocked is stored as part of your bioware profile, as long as you can remember the email | password then this new gog game will have all the unlocks you got before and it doesn't matter if you don't have old save game files.

Doesn't seem to work for me, though.

I unlocked everything there was to unlock on the Xbox 360, uploaded to Bioware's Social page and registered there, but I can't get it to unlock anything on my GOG PC installation.

Maybe it just doesn't work cross platform, which is a shame.

Guess I'll just go straight for another nightmare run, get everything again.

Same here.

I think the respec Mod also lets you unlock specializations:
http://www.nexusmods.com/dragonage/mods/14/?

Must have Mod IMO.

Sorry, but when I click on your link, the description of the mod says (among other things).

MPORTANT
=========
This mod pokes around with your character statistics, use it at your own risk.
At least save your game before you try it!

The mod does not grant you character specializations that are tied to the campaign,
such as Champion, Reaver, Blood Mage and Duelist. However, if you have acquired these
specializations throughout the storyline you are not losing them either.

You can use the Raven NPC to learn all of the specialization skills that can be bought
from the vendors. This is mainly to help people respec low level characters that have a
specialization (Morrigan, Alistair, ..) before the player had any chance of acquiring
the respective specialization books.

At least in origins, some specialisations can not be bought as book.
I have read that some of them can be bought in awakening.
I am not sure if those can be addad with the mod and if every specialisation is avaiable that way.

I must admit that I have not installed DA:O already (still palying something else).
Could somebody please check if this mod can do this?

If it does not work I have to do it like everybody else who plays the game for the first time. You can definitely finish the game without a blood mage and when getting the other specialisations a bit later in the game.

Ok, I thought it could teach specializations, but apparently only the ones you could buy, but not all of them.

Still a very useful mod for it's respec capability.

But not what you are looking for.

Looks like my problems have been solved.
When I installed the game I found out that all of my saves and achievments are still there.
After looking through the computer, I found that the old installation is still there.
Maybe I did just delete the desktop icon a long time ago and I have forgotten that I had installed the game on this computer.

Where are the saves? I looked through the computer and found all kind of saves for all kind of games, but not this one.

Saves are Under your:

"Documents" folder.

Then Bioware/Dragon Age/Characters/CharName/Saves