game is starting normaly, but its openning in a small window. I change settings and is still wont open on a full screen.

Tried hitting Alt+Enter? That should toggle between window and fullscreen.

Is this the original Dungeon Keeper? As flickas said, Alt+Enter should make the game go fullscreen. I had another DOSBox game, Duke Nukem 3D, start in a window at one point, and Alt+Enter worked to fill up.

Support should be able to help, but this may help also as I believe this person had a similar problem: http://www.gog.com/forum/realms_of_the_haunting/changing_the_size_of_the_dosbox_window/post2

still nothing change. just gave up

Make sure you contact Support.

i did just have to wait for the answer, thanks for help any way

- Run "Launch Graphic Mode Setup" as administrator (right-click => Run as...); It's in the "\Dungeon Keeper Gold" folder
- In "Basic Settings" change "Graphic mode" to DDraw, check "Full Screen"
- In "Advanced Settings" check "Keep Aspect Ratio" if you don't want a stretched picture on a widescreen monitor
- Save Settings

If it's still a little box in the middle of the screen:
- Open \Dungeon Keeper Gold\dosboxDK.conf with an editor (e.g. WordPad)
- In the section [sdl] set "fullresolution" to your desktop resolution (e.g. fullresolution=1680x1050)

For the Deeper Dungeons add-on:
- Edit \Dungeon Keeper Gold\dosboxDK_addon.conf instead
- If fullresolution= is missing, add it under [sdl] and set your desktop resolution

You might have to login as Administrator or run the Windows Explorer as Administrator to be allowed to edit these files (or run WordPad as Administrator and open the files from there). If so, also run the game with Administrator rights.

Trying to follow your instructions and hit a stumbling block in that i cannot find 'Basic settings' in the Dungeon keeper game folder.
And how would i launch graphic mode setup? sorry if this sounds like complete idiocy. I have zero experience with PC gaming and no idea what im doing when it comes to changing programs I have located The graphics menu was under 'DOSBox Configuration' The game still boots up on a small window surrounded by black.

To get the best results for original Dungeon Keeper in DOSBox edit the config file manually.

1. Open a text editor, like WordPad and open the file: dosboxDK.conf
It's inside the game's installation folder (e.g. C:\GOG Games\Dungeon Keeper Gold\dosboxDK.conf); The location depends on where you've installed the game;

2. Now edit the following entries, so that they look like this:

fullscreen=true

fullresolution=1680x1050

output=openglnb

The value you have to use for fullresolution has to be your monitor's native resolution (usually the biggest you can use on your machine);

Save the file and start DungeonKeeper as usual.

However, if you want to play in a higher resolution and with additional fixes, check the community mod KeeperFX. You'll find everything about it in this thread:
https://www.gog.com/forum/dungeon_keeper_series/keeperfx_hires_dk1_latest_builds_and_install_instructions

Actually, if it's black all around, then it's not a matter of it being in a window, but there is no scaling done.

Open your NVIDIA/ATI control panel, look for "Scaling" and select "Maintain Aspect Ratio" to be in full screen but with correct aspect ratio. Alternatively, you can select "Full Screen" for complete full-screen, but an ugly/stretched image.
Quoting for notification.