Hi Sandy, welcome to NST.
What problem are you trying to fix ?
If you need to completely reinstall from external media, you'll need to go to Acer themselves if you didn't take the precaution of making your own bootable media when the PC was new.
If the Acer recovery partition (hidden) is still there you should be able to access it with Alt F10 as you power-up.
If it's still there but the boot process is broken, you can use our recovery disk to repair the boot. (not reinstall Vista), after which you can restore the proper function of the hidden partition by rebuilding the Acer MBR as described here.