Acer Aspire One laptop, virus?

My mom's Acer Aspire One D270-1375 just got really messed up. She downloaded something and right after that, her computer crashed and failed to start back up again successfully. It starts up halfway, but once it gets to the Welcome screen, the password box and everything are not there. It then proceeds to flash between a black screen and the blank Welcome screen.

Since I can't get into the computer, how can I perform a System Reset or Restore? Is there any way to save this laptop? I tried accessing the Setup using F2 but I have no idea what any of that stuff is. I'm not a very code-savvy/technical person. Any help would be appreciated, thanks!

Edit: her laptop runs Windows 7, if that's any help.

 

Hopefully not too late...
Your Moms Computer has a built-in Recovery system -

1. Power on your computer. When the Acer logo is displayed,
2. press and hold the ALT key while pressing repeatedly the F10 key. Release the keys when a message displays that Windows is loading files.
3. After the system recovery program has loaded follow the prompts to reinstall the operating system
4. In case the recovery software does not start, you need to use Recovery DVDs or CDs; please visit our knowledge base article Recovery using CDs or DVDs.

Hope this was helpful