I have corrupted files and cannot restore to original OS. (was not included in package when it was bought.) The reviews on Mountain Lion is not good so I am hesitant what to do....and suggestions??

Holding down the Alt/Option key at Startup runs a ROM routine that show an icon for each potentially-bootable drive. Choose Recovery_HD, if available.

Use Recovery_HD to re-download and re-Install the OS you already have (do not buy a new one). Internet connection required.

You can purchase Snow Leopard here. You will not find a Recovery_HD if you are using 10.6.8.

What is the current OS?

Look in  > 'About this Mac' and read the OS X version.

Then click on the 'More info' button and read the hardware identifier for us (will look like MacBook Pro2.2, but probably with a different number).

When we know these things we can better advise you of possible ways to proceed.

Addendum: Mountain Lion seems to have split opinion somewhat. Frankly I have no use for it and will be sticking with Snow Leopard; not least be able to continue using my large collection of Appleworks DB files. Lion and ML no longer support the software needed to run AppleWorks on the Intel platform.

Message was edited by: noondaywitch

If running 10.6.8, the exact model of Mac is vitally important. The last "Full Retail" DVD has 10.6.3. Some models require a custom 10.6.3 or even later, and will not boot the "Full Retail" version.

For those Macs, boot discs are only available by ording a special "Replacement disc" for the version that shipped in your Mac. Some Apple "first responders" are badly trained on this issue, so you have to be a little pushy and get to a Mac specialist. Have your serial number at hand when you call.

I am not certain which version is on the "Full Retail" 10.6.3 DVD, but I would say there is a slight risk your Mac will not boot with that DVD.

AppleCare is geared for a high Volume of callers. They want your serial number up front to pre-sort the incoming calls. Not having it at hand delays your call.

Some "first responders" MAY tell you DVDs are not available, period. If that is the response you get, ask for a specialist in your product. They can run your serial number through a database and figure out whether replacement discs are actually available. If they are, they can send you one for a nominal fee, typically about US$25.

When I have ordered these, I was sent a white-faced DVD-R with printed Apple logo that says the computer type, e.g, "15-inch MacBook Pro", and "Replacement DVD, Not for Resale" and a part number.

It will be an Installer/Utilities DVD, equivalent in function to the "Full Retail" 10.6 DVD.

To use it, you boot from it. In cases where there is no pre-existing Mac OS X, Hold down the Alt/Option key at Startup. This invokes the All-in-ROM Startup Manager, which draws an icon for each potentially bootable Volume available. When it has completed its first scan, the Eject key goes "live" and can be used to open the DVD drawer on a tray-loader DVD drive (if so equipped). Insert the DVD and it will re-scan.

Select the Icon for the Disc ("Install Mac OS X" is its likely name) and press the proceed arrow.

If you need to initialize a drive first, answer only the "What language" question, and do not proceed. Wait a quarter minute for the menuBar to be drawn, and choose Disk Utility off one of the Menus.

I finally found what I was looking for:

Retail installation disc build numbers

--from:

Finding your OS X version and build information

Since you need 10D2125, and the 10.6.3 "Full Retail" Installer will be 10D575,

it will probably NOT boot your MacBook.

.

Yes, 10D2125 is what they should send you as a Replacement disc, or later version with Drivers for your specific model (and no drivers for any other models).

From the chart they could also send you 10F2108, depending on what shipped with your Mac originally.