Does your Mac fails to boot after installing any software or upgraded operating system. This is common problem for many mac users which may lead to data loss from your Mac system. You may have installed any malicious program that is inhibiting the system from booting up, or the operating system was not upgraded and installed properly. You can try to boot up the Mac in the safe mode which will not start any unnecessary program and you can use the Mac OS X in the default setting. Now you can find why Mac fails to boot after installing. If it is due to a program then you can uninstall it and if it is because of the operating system itself then you may have to reinstall the Mac OS X and properly upgrade it this time. This may fix Mac fails to boot after installing issue but it will also result in data loss. Now to recover the lost data either you use a backup or else Mac data recovery software is available for you. If scans the Mac drive for erased data and then show the scan results in the preview. Select the files for restoring them in Mac.