Good morning, Eva. My name is***** am a computer professional with over 15 years of experience with both Mac and Windows. I'm sorry that you're having this issue. It would be my pleasure to help you resolve this. Can you tell me please what Operating System you have on your computer?
Can you click this link and tell me what you see please?
From the Apple menu, choose About This Mac. Your version of OS X appears directly below “OS X
Once I know that I can provide you with detailed instructions for running the installation program from the cd, or if you prefer I can connect remotely and run it for you. Just let me know your preference.