Restart computer, and watch the screen closely.
At some point, while still with black screen, you'll see some options at the bottom of the screen.
If you see something like:
F11 - recovery/restoration (or something similar)
it means, you have Recovery Partition.
(I believe, it's F11 key in eMachines case)
If you press F11, you may/may not have further options:
Non-Destructive System Restore (Recommended) recovers the operating system, all programs, and hardware drivers that were installed at the factory. Your data files should not be damaged with this process.
Full System Restore (Destructive) reformats the hard drive and restores the system software as it was when you purchased your computer. Your data files are not restored with this process.