replacing hard drive

Hi

Please could someone help with replacing the hard drive for a dell inspiron 1545 laptop. Needing to replace the hard drive as computer did not boot up and was going into recovery mode. The screen would turn black with moving cursor. I cannot find any installation discs with the laptop which is about approx 8 years old. I have fitted the new hard drive but now when I turn the laptop on it says it cannot boot up. Unsure what to do next.

Thanks