Mac black screen on start up can really create a panic in the user. Most of the case it happens when the Mac system was not closed properly on the last occasion. The probable reason is that the operating system is not getting loaded in the memory so that the Mac isn't booting. When there is any problem with the startup disk where the operating system was installed then Mac black screen on start up problem is shown to the user. The corruption can caused by any partitioning error, file system damage, virus infection and accidental shut down between any process. You can use the disk utility to shoot out any disk problem and if it is not solved then you have to format the drive. After the formatting the mac black screen on start up can be resolved but the data will be lost from the Mac drive. You can get back the data from the time machine backup and if the backup is not successful then you can use the Mac data recovery software. The software has an efficient way to scan the drive and results are shown in the preview which can be restored upon selection. So get the software now and use it.