How Can I Fix My Dell Pc That Won T Boot

With: 4gb RAM

AMD Athlon II

ATI Raedoen HD 4200

And running windows 7

I recently found out I had a corrupted OS and

tried to reinstall Windows 7 without the setup disk.

(I lost it)

Then the setup failed and it shut down.

Now it just shows the Dell loading screen and that’s all, but it does let me go to boot setup.