Commercial PCs that don't come with a Recovery CD or DVD always have a "Recovery Partition" on the hard drive. You use it by hitting a special Key during the boot process. It will restore the hard drive to "as new", but it may overwrite any data you've put on your PC. Read your Owner's Manual about this.
If you need data files back, and if the hard drive is still semi-functional, then you'll need a software-based data recovery program or you'll need to call in a professional. GetDataBack is often recommended, and costs $80 for a license. I ASSUME it'll work fine with a Vista installation.
If the hard drive is "kaput", then you'll need a hard drive hardware-based data recovery. That is very pricey.
Once you get the data back, you can decide if the hard drive is usable. Run the hard drive maker's diagnostics tests. You should also immediately contact Acer and tell them you'd like a System Recovery disk for your PC. You MAY have to pay for it, and I strongly suggest you do so. If your PC originally came with Vista, I'd think it's still under warranty.....
Summary:
1) Call Acer Support and ask for a Recovery Disk
2) Get your data back
3) Test the hard drive
3) Re-install Vista and your data, either on the original drive or on a new one. If your PC is under warranty, then Acer would do this for you.