can't upgrade from mountin lion to yasimite

Why not? What happen when you attempt to do that?

Have you tried:

Repair the Hard Drive and Permissions - Yosemite, Mavericks, Mountain Lion or Lion

Boot to the Recovery HD:

Restart the computer and after the chime press and hold down the COMMAND and R keys until the menu screen appears. Alternatively, restart the computer and after the chime press and hold down the OPTION key until the boot manager screen appears. Select the Recovery HD and click on the downward pointing arrow button.

Repair

When the recovery menu appears select Disk Utility and press the Continue button. After Disk Utility loads select the Macintosh HD entry from the the left side list. Click on the First Aid tab, then click on the Repair Disk button. If Disk Utility reports any errors that have been fixed, then re-run Repair Disk until no errors are reported. If no errors are reported click on the Repair Permissions button. Wait until the operation completes, then quit Disk Utility and return to the main menu. Select Restart from the Apple menu.

Now, re-run the Yosemite installer application or re-download it if you don't have it yet. If you are getting server errors, then you will need to check your internet connection and service or wait to try another time.

Yes

Yes. You can upgrade from Snow Leopard 10.6.8, Lion, Mountain Lion, or Mavericks to Yosemite. No need to upgrade to all of them. You can upgrade from any one of them.

What version of OS X was originally installed on your computer? Are you thinking of erasing the drive and installing Lion before upgrading to Yosemite?

Where did you get a cd for Mountain Lion?

Mountain Lion was never available on CD. It was only available an online download.

Are you sure you have Mountain Lion and not an earlier release of OS X that was available on CD?

I'm not following. Mountain Lion does not come on a CD or DVD. You must purchase and download Mountain Lion from the App Store. If you purchased it in the past you can still re-download it.

Please provide complete information. It isn't clear what you are doing. If you are running 10.4 Server, then you will need to erase it in order to install any OS X upgrade starting from Snow Leopard.

If you purchase it in 2009 it is certainly not either Mountain Lion 10.8 or anything newer seeing as how 10.8 was released in 2012.

It is most likely Leopard 10.5 which did come on a CD.

So you need to purchase from Apple the CD for Snow Leopard 10.6 which is required to get to anything above that using the App Store to download it.

There was no Yosemite in 2009. It probably came with discs for Leopard. Furthermore, you cannot get Yosemite on a DVD. Whatever you see on that label it isn't the OS X version. I'm thinking your computer has 10.5.x installed on it which is why you are unable to download it completely.