install mountain lion from usb without internet

Whenever possible, you should back up the Mac with Time Machine before attempting this.
Download Oountain Lion and Extract the DMG File.
You can also use CommandR to boot into Recovery mode, older Mac models that do not support Internet Recovery will best sex game apps for pc need to do that.Go to the /Applications/ directory and right-click on Install Mac Oountain Lion.Open Mac Disc Utility and Erase the USB drive in Mac OS Extended (Journaled) format.Note: Re-installing OS X is typically only necessary when something is seriously wrong with the Mac system software and the computer is not functioning as it should.You can always start a backup with Time Machine before if you need.Make the Oountain Lion Install Drive.That difference in how the two features works means you could theoretically use Internet Recovery to downgrade OS X to the version that shipped with the Mac, though there are better ways to do that if you have a Time Machine backup from the prior.Confirm that the USB drive will lose its data and enter the Admin password when asked.This is made fairly easy as all modern Macs include the Onternet Recovery feature, which lets you reinstall OS X through a netboot type of mode that is accessed from the internet rather than a local drive.This kind of installation process is a bit displeasing for people those who have throttled broadband bandwidth and slow internet connections.If interested in going that route, you can learn about clean installing Oosemite, or clean installing Oavericks, both of which are best performed from a separate boot drive or bootable USB installer.
And it supports re-installation of the OS in offline mode without an internet connection.
Disk Utility will now create a bootable Oountain Lion installer drive out of USB drive using the disk image, this can take a little while depending on how fast the drive and Mac are but 20-30 minutes isnt unusual.