Hey guys i just bought and downloaded disciples sacred lands on my netbook and it wont let me play because i dont have a cd/dvd drive.... Can someone please explain to me how to get around this?

Try installing Virtual CloneDrive.

http://www.slysoft.com/en/download.html

It's free, and it'll make your system think it has a DVD/CD drive.

I tried.... but i need some like ISO thing to emulate it... and i dont know how to get that without disc?

The GOG version is asking for a disc...?

Well you can burn it to a CD or DVD, then extract the ISO from that.

EDIT: Removed. It became apparent this may not be the GOG version.

Ok, lets be honest here... are you actually using the GOG version or did you get it from somewhere else?

If it's the GOG version uninstall, delete any remaining files in the original install directory, and then run the install again.

If its a Gog game it shouldn't need a CD-Drive, try contacting support. However for an ISO file I would use daemon tools. Make sure you get the lite version, the rest you have to pay for.
http://www.daemon-tools.cc/eng/products/dtLite