Hi,
Before you try the Digital River download ( it is legal ) try this:
Switch on and constantly tap F8 about once per second.
This will take you to the Advanced Boot Options.
There should be an option "Repair your Computer" ..........if there is ....give this a try.
Alternatively ....
Acer usually have a recovery partition.
Switch on ...... hold CTRL down and tap F10
NOTE:
Using the recovery partition or the Digital River solution will wipe all content off the hard drive.
The recovery method will revert the computer to exactly how it was when first bought - including all of the bloatware ( Anti-Virus free trial etc etc )
You will lose all installed software - saved files - photos etc.
It may be possible to access these if you take the hard drive out and connect it to another machine using an external enclosure or hard drive to USB adapter. ( both are quite cheap to buy )