Hey DianeVall,
I'm sorry you're running into this error, but I'm sure we can get it straightened out :)
With that error message, something has caused the computer to look for a Windows disc to be in the CD tray, because it has been told to boot from the CD tray. All you should need to do is change the Boot Order in BIOS, so that it no longer looks to the CD tray first, but to the hard drive.
If you've had an upgrade or had to reinstall Windows recently, that is probably the reason for that.
To change the Boot Order in BIOS:
1. Power down the computer
2. Press the Power button and immediately start tapping the F10 key repeatedly to enter BIOS.
3. You'll see tabs across the top of the BIOS screen. Use your arrow keys and arrow Right over to Storage.
4. On the System Configuration screen, arrow Down to Boot Order and press Enter.
5. Arrow Down to select Hard Drive and press Enter.
6. Arrow Left to File and down to Save Changes and Exit.
Then Windows should load normally. Have you made any changes like I mentioned, recently? Reinstalled Windows or had to use a repair disc or anything?
If those options I mentioned in the steps above don't look like what you see in your BIOS, please take a picture of your BIOS and post it in your reply, or let me know what the version number and BIOS maker name are. Usually that information is on the first/home/main screen in BIOS, either at the very top or very bottom. Look for the Copyright symbol and let me know the information beside it.
I hope these steps help! I'll keep an eye out for your reply :)