Hi im new here. I've got morrowind since 2004 but I cant install bloodmoon now It's a problem with data2.cab, what to do? Can some1 tell me where to get the bloodmoon.esm or something like this?

1) I hope you're not referring to downloading it! Which is illegal as I recall and you're not allowed to refer to it here.
2) Just keep trying to install it. I don't think there's anything you can do about the error, but not giving up sometimes works.

Checked the disk for scratches or such? It's possible it got damaged somehow. Apart from that as Kzinist says, keep trying. Not really much else you can do. If you want to go for the illegal download route you'll have to do so elsewhere, as we don't allow that here.