my computer IS ACER ASPIRE 4750z
This forum is "Windows Vista System Repair and Recovery". You are looking for "Acer". ;-)
If the ALT+F10 does not work for your system... Contact the manufacturer to find out what method you are to use to restore your system to Factory Defaults (assuming you, not being the original poster, are looking to do the same thing) and/or look through
the materials that came with your system for the instructions.
However, the ALT+F10 is shown to work.
When the Acer logo appears on the screen, press the Alt and F10 keys TOGETHER repeatedly.
If you are prompted with a Microsoft Windows boot screen, press the Enter key.
After the system recovery application has loaded, follow the prompts to reinstall the Operating System. Your laptop will reload Windows and all Acer applications and files that were originally on the computer when you bought it. You will begin from day 1 all
over again.
You will lose everything you have done/put on the system that you have not backed up.